uu.seUppsala universitets publikationer
Ändra sökning
Avgränsa sökresultatet
3456789 251 - 300 av 1425
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 251. Ehlers, G.
    et al.
    Mamontov, E.
    Zamponi, M.
    Kam, K. C.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Gardner, J. S.
    Direct Observation of a Nuclear Spin Excitation in Ho2Ti2O72009Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 102, nr 1, s. 016405-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A single nondispersive excitation is observed by means of neutron backscattering, at E-0=26.3 mu eV in the spin ice Ho2Ti2O7 but not in the isotopically enriched (Dy2Ti2O7)-Dy-162 analogue. The intensity of this excitation is rather small, less than or similar to 0.2% of the elastic intensity. It is clearly observed below 80 K but resolution limited only below similar to 65 K. The application of a magnetic field up to mu H-0=4.5 T, at 1.6 K, has no measurable effect on the energy or intensity. This nuclear excitation is believed to perturb the electronic, Ising spin system resulting in the persistent spin dynamics observed in spin ice compounds.

  • 252. Eklund, P
    et al.
    Emmerlich, J
    Högberg, H
    Wilhelmsson, Ola
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. oorganisk kemi.
    Isberg, P
    Birch, J
    Persson, P. O. Å.
    Jansson, Ulf
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. oorganisk kemi.
    Hultman, L
    Structural, electrical, and mechanical properties of nc-TiC/a-SiC nanocomposite thin films2005Ingår i: Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, Vol. 23, nr 6, s. 2486-2495Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have synthesized Ti–Si–C nanocomposite thin films by dc magnetron sputtering from a Ti3SiC2 compound target in an Ar discharge on Si(100), Al2O3(0001), and Al substrates at temperatures from room temperature to 300 °C. Electron microscopy, x-ray diffraction, and x-ray photoelectron spectroscopy showed that the films consisted of nanocrystalline (nc-) TiC and amorphous (a-) SiC, with the possible presence of a small amount of noncarbidic C. The growth mode was columnar, yielding a nodular film-surface morphology. Mechanically, the films exhibited a remarkable ductile behavior. Their nanoindentation hardness and E-modulus values were 20 and 290 GPa, respectively. The electrical resistivity was 330 µ cm for optimal Ar pressure (4 mTorr) and substrate temperature (300 °C). The resulting nc-TiC/a-SiC films performed well as electrical contact material. These films' electrical-contact resistance against Ag was remarkably low, 6 µ at a contact force of 800 N compared to 3.2 µ for Ag against Ag. The chemical stability of the nc-TiC/a-SiC films was excellent, as shown by a Battelle flowing mixed corrosive-gas test, with no N, Cl, or S contaminants entering the bulk of the films.

  • 253. Eklund, P.
    et al.
    Joelsson, T.
    Ljungcrantz, H.
    Wilhelmsson, Ola
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Czigany, Zs.
    Högberg, H.
    Hultman, L.
    Microstructure and electrical properties of Ti-Si-C-Ag nanocomposite thin films2007Ingår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 201, nr 14, s. 6465-6469Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ti-Si-C-Ag nanocomposite coatings consisting of nanocrystalline TiC in an amorphous Si matrix with segregated Ag were deposited by dual magnetron sputtering from Ti3SiC2 and Ag targets. As evidenced by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, for Ag contents below 10 at.%, the Ag forms similar to 10 nm large crystallites that are homogeneously distributed in the films. For higher Ag contents, coalescence during growth results in the formation of > similar to 100 nm Ag islands on the film surface. The electrical resistivity of the coatings was measured in a four-point-probe setup, and ranged from 340 mu Omega cm (for Ti-Si-C coatings without Ag) to 40 mu Omega cm (for high Ag content).

  • 254. Eklund, Per
    et al.
    Beckers, Manfred
    Jansson, Ulf
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    Högberg, Hans
    Hultman, Lars
    The Mn + 1AXn phases: Materials science and thin-film processing2010Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 518, nr 8, s. 1851-1878Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    This article is a Critical review of the M(n + 1)AX(n) phases ("MAX phases", where n = 1, 2, or 3) from a materials science perspective. MAX phases are a class of hexagonal-structure ternary carbides and nitrides ("X") of a transition metal ("M") and an A-group element. The most well known are Ti2AlC, Ti3SiC2, and Ti4AlN3. There are similar to 60 MAX phases with at least 9 discovered in the last five years alone. What makes the MAX phases fascinating and potentially useful is their remarkable combination of chemical, physical, electrical, and mechanical properties, which in many ways combine the characteristics of metals and ceramics. For example, MAX phases are typically resistant to oxidation and corrosion, elastically stiff, but at the same time they exhibit high thermal and electrical conductivities and are machinable. These properties stem from an inherently nanolaminated crystal structure, with M1 + nXn slabs intercalated with pure A-element layers. The research on MAX phases has been accelerated by the introduction of thin-film processing methods. Magnetron sputtering and arc deposition have been employed to synthesize single-crystal material by epitaxial growth, which enables studies of fundamental material properties. However, the surface-initiated decomposition of M(n + 1)AX(n) thin films into MX compounds at temperatures of 1000-1100 degrees C is much lower than the decomposition temperatures typically reported for the corresponding bulk material. We also review the prospects for low-temperature synthesis, which is essential for deposition of MAX phases onto technologically important substrates. While deposition of MAX phases from the archetypical Ti-Si-C and Ti-Al-N systems typically requires synthesis temperatures of similar to 800 degrees C, recent results have demonstrated that V2GeC and Cr2AlC can be deposited at similar to 450 degrees C. Also, thermal spray of Ti2AlC powder has been used to produce thick coatings. We further treat progress in the use of first-principle calculations for predicting hypothetical MAX phases and their properties. Together with advances in processing and materials analysis, this progress has led to recent discoveries of numerous new MAX phases such as Ti4SiC3, Ta4AlC3. and Ti3SnC2. Finally, important future research directions are discussed. These include charting the unknown regions in phase diagrams to discover new equilibrium and metastable phases, as well as research challenges in understanding their physical properties, such as the effects of anisotropy, impurities, and vacancies on the electrical properties, and unexplored properties such as Superconductivity, magnetism, and optics.

  • 255.
    Ekstrand, Åsa
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Novel powder-coating solutions to improved micro-structures of ZnO based varistors, WC-Co cutting tools, and Co/Ni nano-phase films and sponges2002Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Solution chemistry is a versatile and powerful tool in the synthesis of designed, complex nano-level high-tech materials. Normally, the technique is considered too expensive for large-scale production of complex multi-component ceramic materials. This thesis describes the expansion of the useful area of solution processing to multi-component bulk materials such as ZnO-based high-field varistors and WC–Co cutting tools, by developing novel techniques for solution-based coating of conventionally prepared metal and ceramic powders. The chemistry and microstructure development in the preparation of coatings, and the sintering of the coated powders to compacts, were studied in detail by SEM-EDS, TEM-EDS, XRD, IR-spectroscopy, dilatometry, TGA and DSC chemical analysis.

    ZnO powder with a ca 20 nm thick, homogeneous oxide coat of Bi–Sb–Ni–Co–Mn–Cr–Al oxide was prepared. After sintering to dense varistor bodies, much improved microstructures with much reduced ZnO-grain sizes were obtained. This shows that the oxides added as liquid sintering aid and grain-growth inhibitor become much more active when added homogeneously as a skin on the ZnO powder.

    After sintering of cobalt-coated WC, much improved micro-structures were obtained with a much more narrow WC grain-size distribution than that obtained from starting powders mixed by a conventional milling route. Coated powders also obviate the need for the extensive milling of WC and Co powders used in conventional mixing.

    The novel solution route was also applied to preparation of porous sponges and thin films on metal, glass and Al2O3 of sub 20 nm sized Co- or Ni-particles.

    Delarbeten
    1. Preparation of ZnO-based varistors by the sol-gel technique
    Öppna denna publikation i ny flik eller fönster >>Preparation of ZnO-based varistors by the sol-gel technique
    Visa övriga...
    1994 (Engelska)Ingår i: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 4, nr 4, s. 615-621Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    ZnO-based varistors consisting of 96 mol% ZnO and 4 mol% additive oxides (Bi2O3, Sb2O3, NiO, Co2O3, MnO and Cr2O3) have been prepared. Four different procedures have been applied to obtain the starting powder mixture. Three of the procedures involve sol–gel processing of the additive oxide mixture, and in two cases the surface of the ZnO grains has been covered by the additive oxides. The microstructural and phase composition development during the sintering process has been monitored and the electrical properties of the varistors have been determined. Higher breakdown voltages are obtained for varistors produced by sol–gel-processed starting materials, and the highest values are found for varistors prepared from ZnO grains covered with the additive oxides. Phase analysis revealed that the spinel phase, which retards the grain growth of the ZnO particles, is formed at lower temperatures and in larger amounts in these compacts. The higher breakdown voltages of these compacts thus seem to be related to the content of more finely grained ZnO particles in these compacts.

    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:uu:diva-89780 (URN)10.1039/JM9940400615 (DOI)
    Tillgänglig från: 2002-04-03 Skapad: 2002-04-03 Senast uppdaterad: 2017-12-14Bibliografiskt granskad
    2. Processing of ZnO-based varistors using oxide, alkoxide, nitrato-alkoxide and carboxylato precursors
    Öppna denna publikation i ny flik eller fönster >>Processing of ZnO-based varistors using oxide, alkoxide, nitrato-alkoxide and carboxylato precursors
    1997 (Engelska)Ingår i: Journal of Sol-Gel Science and Technology, ISSN 0928-0707, E-ISSN 1573-4846, Vol. 8, nr 1-3, s. 697-701Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    We have investigated the preparation of ZnO varistors by different chemical solution routes with the aim of improving the homogeneity of the phases formed and to obtain a better control of microstructure. One conventional oxide mixing route and four solution chemical routes have been used to prepare the precursor materials. In all cases, the same composition (mol%) was used; ZnO (95.9), Bi2O3 (1), Sb2O3 (1), NiO (1), Co2O3 (0.5), MnO (0.5), Cr2O3 (0.1). The same sintering procedure was also applied. It was found that the precursor materials consisting of ZnO grains covered by a thin film of the additive oxides yielded smaller ZnO grains. Also the microstructure in the final compacts was improved, compared with that of compacts prepared from oxide mixing routes. The smaller ZnO grain size in the final compacts was attributed to the presence of spinel grains. The spinel grains are formed at lower temperatures and, when they reach a size of 1 μm, they hinder the growth of ZnO grains.

    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:uu:diva-89781 (URN)10.1007/BF02436925 (DOI)
    Tillgänglig från: 2002-04-03 Skapad: 2002-04-03 Senast uppdaterad: 2017-12-14Bibliografiskt granskad
    3. Solution Synthesis of Nano-Phase Nickel as Film and Porous Electrode
    Öppna denna publikation i ny flik eller fönster >>Solution Synthesis of Nano-Phase Nickel as Film and Porous Electrode
    2000 (Engelska)Ingår i: Journal of Sol-Gel Science and Technology, ISSN 0928-0707, E-ISSN 1573-4846, Vol. 19, nr 1-3, s. 353-356Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Routes to nano-phase nickel in the forms of highly porous sponges and dense films have been developed.Nickel acetate and nitrate were mixed with triethanolamine and methanol, and evaporated to a concentrated liquid.Heat-treatment at 10±C/min to 170±C under N2 atmosphere yielded a highly porous sponge consisting of <10 nmsized Ni crystallites. Deposition of a 1 M nickel precursor solution on polycrystalline Al2O3, SnO2 : F coated glassor titanium substrates spinning at 2700 rpm, followed by heat-treatment at 10±C/min to 400±C yielded smooth anddense nickel films consisting of 3–5 nm sized crystallites. The precursor concentrate was studied by FT-IR andthe phase development on heat-treatment was studied by thermogravimetric analysis, powder X-ray diffraction,scanning and transmission electron microscopy.

    Nyckelord
    solution processing, nano-phase nickel, film, sponge
    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:uu:diva-89782 (URN)10.1023/A:1008762405755 (DOI)
    Tillgänglig från: 2002-04-03 Skapad: 2002-04-03 Senast uppdaterad: 2017-12-14Bibliografiskt granskad
    4. Homogeneous WC–Co-Cemented Carbides from a Cobalt-Coated WC Powder Produced by a Novel Solution-Chemical Route
    Öppna denna publikation i ny flik eller fönster >>Homogeneous WC–Co-Cemented Carbides from a Cobalt-Coated WC Powder Produced by a Novel Solution-Chemical Route
    2007 (Engelska)Ingår i: Journal of The American Ceramic Society, ISSN 0002-7820, E-ISSN 1551-2916, Vol. 90, nr 11, s. 3449-3454Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    A solution chemical route to cobalt-coated WC-powder is described that allows for the preparation of WC–Co powders and compacts having a carbon content very close to the desired carbon content even under an inert atmosphere. The microstructural homogeneity in the sintered WC–Co composites when using the Co-coated grains was found to be superior as compared with conventionally mill-mixed powders, and the structural changes in the individual WC-grains were found to be much smaller, which is ascribed mainly to the fact that the coated grains do not require a grinding step leading to the formation of a tail of smaller WC grain sizes.

    Nationell ämneskategori
    Kemi
    Identifikatorer
    urn:nbn:se:uu:diva-12096 (URN)10.1111/j.1551-2916.2007.01948.x (DOI)000250762100011 ()
    Tillgänglig från: 2007-11-26 Skapad: 2007-11-26 Senast uppdaterad: 2017-12-11Bibliografiskt granskad
    5. A New Solution Synthetic Route to Nano-Phase Cobalt Film and Sponge
    Öppna denna publikation i ny flik eller fönster >>A New Solution Synthetic Route to Nano-Phase Cobalt Film and Sponge
    Manuskript (Övrigt vetenskapligt)
    Identifikatorer
    urn:nbn:se:uu:diva-89784 (URN)
    Tillgänglig från: 2002-04-03 Skapad: 2002-04-03 Senast uppdaterad: 2010-01-13Bibliografiskt granskad
    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 256.
    Ekstrand, Åsa
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. oorganisk kemi.
    Jansson, K
    Westin, Gunnar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. oorganisk kemi.
    A Solution Synthetic Route to Nanophase Cobalt Film and Sponge2005Ingår i: Chem. Mater, Vol. 17, s. 199-205Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An efficient, low-cost solution-chemical route to nanophase cobalt as dense films and sponges has been developed. Co(NO3)2·6H2O and Co(OAc)2·4H2O were mixed with triethanolamine in methanol, and the solution was evaporated in air to a viscous liquid. Heating at 10 C min-1 to 470 and 500 C yielded highly porous sponges consisting of 3-6 and 9-11 nm sized face centered cubic (fcc) cobalt crystallites, respectively. Spin-coating on alumina and aluminum substrates with a 1 M Co-precursor solution and subsequent heating at 10 C min-1 to 500 C yielded dense films of <20 nm sized fcc cobalt crystallites. The microstructural and compositional evolution process on heating to form the cobalt metal was studied by TGA, DTA, and FT-IR spectroscopy, powder X-ray diffraction, TEM-EDS, and SEM-EDS. The C, N, and O contents could be kept low, 0.5, 0.02, and 0.2 wt %, respectively, at 700 C, but the carbon content could also reproducibly be adjusted to up to 13 wt % C in excess, by varying the precursor composition.

  • 257.
    Ekstrand, Åsa
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Jansson, Kjell
    Westin, Gunnar
    A New Solution Synthetic Route to Nano-Phase Cobalt Film and SpongeManuskript (Övrigt vetenskapligt)
  • 258.
    Ekstrand, Åsa
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Jansson, Kjell
    Westin, Gunnar
    Solution Synthesis of Nano-Phase Nickel as Film and Porous Electrode2000Ingår i: Journal of Sol-Gel Science and Technology, ISSN 0928-0707, E-ISSN 1573-4846, Vol. 19, nr 1-3, s. 353-356Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Routes to nano-phase nickel in the forms of highly porous sponges and dense films have been developed.Nickel acetate and nitrate were mixed with triethanolamine and methanol, and evaporated to a concentrated liquid.Heat-treatment at 10±C/min to 170±C under N2 atmosphere yielded a highly porous sponge consisting of <10 nmsized Ni crystallites. Deposition of a 1 M nickel precursor solution on polycrystalline Al2O3, SnO2 : F coated glassor titanium substrates spinning at 2700 rpm, followed by heat-treatment at 10±C/min to 400±C yielded smooth anddense nickel films consisting of 3–5 nm sized crystallites. The precursor concentrate was studied by FT-IR andthe phase development on heat-treatment was studied by thermogravimetric analysis, powder X-ray diffraction,scanning and transmission electron microscopy.

  • 259.
    Ekstrand, Åsa
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Nygren, Mats
    Westin, Gunnar
    Processing of ZnO-based varistors using oxide, alkoxide, nitrato-alkoxide and carboxylato precursors1997Ingår i: Journal of Sol-Gel Science and Technology, ISSN 0928-0707, E-ISSN 1573-4846, Vol. 8, nr 1-3, s. 697-701Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have investigated the preparation of ZnO varistors by different chemical solution routes with the aim of improving the homogeneity of the phases formed and to obtain a better control of microstructure. One conventional oxide mixing route and four solution chemical routes have been used to prepare the precursor materials. In all cases, the same composition (mol%) was used; ZnO (95.9), Bi2O3 (1), Sb2O3 (1), NiO (1), Co2O3 (0.5), MnO (0.5), Cr2O3 (0.1). The same sintering procedure was also applied. It was found that the precursor materials consisting of ZnO grains covered by a thin film of the additive oxides yielded smaller ZnO grains. Also the microstructure in the final compacts was improved, compared with that of compacts prepared from oxide mixing routes. The smaller ZnO grain size in the final compacts was attributed to the presence of spinel grains. The spinel grains are formed at lower temperatures and, when they reach a size of 1 μm, they hinder the growth of ZnO grains.

  • 260.
    Ekstrand, Åsa
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. oorganisk kemi.
    Westin, Gunnar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. oorganisk kemi.
    Highly homogeneous WC-Ni/Co Composites Produced from WC-Powder coated with a Solution Chemical Route2002Ingår i: 10th International Ceramics Congress 2002 Proceedings, 2002, s. 489-Konferensbidrag (Refereegranskat)
  • 261.
    Ekstrand, Åsa
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Westin, Gunnar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Nygren, Mats
    Homogeneous WC–Co-Cemented Carbides from a Cobalt-Coated WC Powder Produced by a Novel Solution-Chemical Route2007Ingår i: Journal of The American Ceramic Society, ISSN 0002-7820, E-ISSN 1551-2916, Vol. 90, nr 11, s. 3449-3454Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A solution chemical route to cobalt-coated WC-powder is described that allows for the preparation of WC–Co powders and compacts having a carbon content very close to the desired carbon content even under an inert atmosphere. The microstructural homogeneity in the sintered WC–Co composites when using the Co-coated grains was found to be superior as compared with conventionally mill-mixed powders, and the structural changes in the individual WC-grains were found to be much smaller, which is ascribed mainly to the fact that the coated grains do not require a grinding step leading to the formation of a tail of smaller WC grain sizes.

  • 262.
    Ekstrand, Åsa
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. oorganisk kemi.
    Westin, Gunnar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. oorganisk kemi.
    Pohl, Annika
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. oorganisk kemi.
    Lafton, J
    Solution synthesis of Cobalt-Copper Nano Phase Films and Sponges2005Ingår i: 13:th International Workshop on Gels and Glasses, Los Angeles, 2005, 2005, s. 2-Konferensbidrag (Refereegranskat)
  • 263. Elihn, K
    et al.
    Landström, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Alm, Oscar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    Boman, Mats
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    Heszler, Peter
    Size and structure of nanoparticles formed via ultraviolet photolysis of ferrocene2007Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 101, nr 3, s. 034311-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Iron nanoparticles enclosed in carbon shells were formed by laser-assisted chemical vapor decomposition of ferrocene (Fe(C5H5)2) vapor in Ar gas atmosphere. The particle size dependence on the total ambient gas pressure and on laser fluence of the pulsed ArF excimer laser was examined and, e.g., an effective size decrease of the iron core was observed at elevated laser fluences. Characterizations of the iron and carbon microstructures were performed by x-ray diffraction and transmission electron microscopy, while relative iron deposition rates were measured by x-ray fluorescence spectroscopy. Both -Fe and -Fe phases were found for the single crystalline iron cores, surrounded by graphitic (inner) and amorphous (outer) carbon layers. The temperature rise of the laser-excited particles was also determined by optical spectroscopy of the emitted thermal radiation, which allowed an estimation of the iron loss of the nanoparticles due to evaporation. The estimated and measured iron losses are in good agreement.

  • 264.
    Elihn, K
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. oorganisk kemi.
    Otten, F
    Boman, Mats
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. oorganisk kemi.
    Kruis, FE
    Fissan, H
    Carlsson, Jan-Otto
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. oorganisk kemi.
    Nanoparticle formation by laser-assisted photolysis of ferrocene.1999Ingår i: NANOSTRUCTURED MATERIALS, ISSN 0965-9773, Vol. 12, nr 1-4, s. 79-82Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Laser-assisted formation of iron-containing nanoparticles has been performed by photolytic dissociation of ferrocene vapour by a pulsed ArF excimer laser at 193 nm. The process was carried out at atmospheric pressure, either in an inert atmosphere of argo

  • 265.
    Elihn, Karine
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Synthesis of carbon-covered iron nanoparticles by photolysis of ferrocene2002Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    One important driving force in nanotechnology today is the change which can be made in the properties of a material when the dimensions of its individual building blocks are decreased below approximately 100 nm. Such small building blocks, typically nanoparticles, may induce new and unique properties compared to those of the corresponding bulk material. The challenge in nanotechnology is to make nanoparticles with a discrete particle size within the range 1-10 nm. It is also important to develop appropriate assembly methodologies in order to construct devices composed of such small building blocks.

    This thesis reports iron nanoparticle synthesis using laser-assisted photolysis of ferrocene. The particles were protected against oxidation by a carbon shell formed in situ during their growth. By varying the experimental conditions such as fluence, repetition rate and laser beam area, particles could be synthesized in the size range 1 to 100 nm. Their size was measured using a differential mobility analyser (DMA), transmission electron microscopy (TEM) and X-ray diffraction (XRD). DMA was also used successfully to size-select particles to facilitate the deposition of monodisperse nanoparticle films.

    A theoretical "residence time approach (RTA)" model was developed to relate particle volume to the laser parameters used. The growth of these particles was studied in situ using optical emission spectroscopy; the results were compared with those from quantum mechanical calculations. The particles were characterised ex situ by TEM, convergent beam electron diffraction, XRD, X-ray photoelectron spectroscopy and Raman spectroscopy. Results from the TEM investigations revealed that the carbon shell was graphitic close to the iron core, while the outer part of the carbon shell was amorphous, indicating different growth mechanisms. Both bcc and fcc iron particles were observed.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 266.
    Elihn, Karine
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. oorganisk kemi.
    Larsson, Karin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. oorganisk kemi.
    A theoretical study of the thermal fragmentation of ferrocene2004Ingår i: Thin Solid Films, nr 458, s. 325-329Artikel i tidskrift (Refereegranskat)
  • 267.
    Elihn, Kristina
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi. strukturkemi.
    Otten, F
    Boman, Mats
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi. oorganisk kemi.
    Heszler, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Kruis, FE
    Fissan, H
    Carlsson, Jan-Otto
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi. oorganisk kemi.
    Size distributions and synthesis of nanoparticles by photolytic dissociation of ferrocene2001Ingår i: APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING, ISSN 0947-8396, Vol. 72, nr 1, s. 29-34Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Iran-containing nanoparticles were made by laser-assisted (ArF excimer laser, lambda = 193 nm) photolytic dissociation of ferrocene (Fe(C5H5)(2) or FeCp2) in argon and an oxygen/argon gas mixture. The particle-size distributions were obtained on-line by u

  • 268. Emmerlich, Jens
    et al.
    Högberg, Hans
    Sasvári, Szilvia
    Persson, Per O. Å
    Hultman, Lars
    Palmquist, Jens-Petter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    Jansson, Ulf
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    Molina-Aldareguia, Jon M
    Czigány, Zsolt
    Growth of Ti3SiC2 thin films by elemental target magnetron sputtering2004Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 96, nr 9, s. 4817-4826Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Epitaxial Ti3SiC2(0001) thin films have been deposited by dc magnetron sputtering from three elemental targets of Ti, C, and Si onto MgO(111) and Al2O3(0001) substrates at temperatures of 800–900 °C. This process allows composition control to synthesize Mn + 1AXn (MAX) phases (M: early transition metal; A: A-group element; X: C and/or N; n = 1–3) including Ti4SiC3. Depositions on MgO(100) substrates yielding the Ti–Si–C MAX phases with (105), as the preferred orientation. Samples grown at different substrate temperatures, studied by means of transmission electron microscopy and x-ray diffraction investigations, revealed the constraints of Ti3SiC2 nucleation due to kinetic limitations at substrate temperatures below 700 °C. Instead, there is a competitive TiCx growth with Si segregation to form twin boundaries or Si substitutional incorporation in TiCx. Physical properties of the as-deposited single-crystal Ti3SiC2 films were determined. A low resistivity of 25 µ cm was measured. The Young's modulus, ascertained by nanoindentation, yielded a value of 343–370 GPa. For the mechanical deformation response of the material, probing with cube corner and Berkovich indenters showed an initial high hardness of almost 30 GPa. With increased maximum indentation loads, the hardness was observed to decrease toward bulk values as the characteristic kink formation sets in with dislocation ordering and delamination at basal planes.

  • 269. Emmerlich, Jens
    et al.
    Music, Denis
    Eklund, Per
    Wilhelmsson, Ola
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    Jansson, Ulf
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    Schneider, Jochen M.
    Högberg, Hans
    Hultman, Lars
    Thermal stability of Ti3SiC2 thin films2007Ingår i: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 55, nr 4, s. 1479-1488Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The thermal stability of Ti3SiC2(0 0 0 1) thin films is studied by in situ X-ray diffraction analysis during vacuum furnace annealing in combination with X-ray photoelectron spectroscopy, transmission electron microscopy and scanning transmission electron microscopy with energy dispersive X-ray analysis. The films are found to be stable during annealing at temperatures up to 1000 °C for 25 h. Annealing at 1100–1200 °C results in the rapid decomposition of Ti3SiC2 by Si out-diffusion along the basal planes via domain boundaries to the free surface with subsequent evaporation. As a consequence, the material shrinks by the relaxation of the Ti3C2 slabs and, it is proposed, by an in-diffusion of O into the empty Si-mirror planes. The phase transformation process is followed by the detwinning of the as-relaxed Ti3C2 slabs into (1 1 1)-oriented TiC0.67 layers, which begin recrystallizing at 1300 °C. Ab initio calculations are provided supporting the presented decomposition mechanisms.

  • 270. Engelhardt, E.
    et al.
    Aibibu, D.
    Gries, T.
    Hilborn, Jöns
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Polymerkemi.
    Adam, M.
    Wurm, F.
    GFP expressing cell line as screening tool for biomaterials2007Ingår i: TERMIS-EU Meeting Abstracts London, UK September 4–7, 2007: [published in Tissue Engineering, vol. 13, nr. 7], Mary Ann Liebert Inc. , 2007, Vol. 13, nr 7, s. 1702-1702Konferensbidrag (Övrigt vetenskapligt)
  • 271. Engelhardt, E.-M.
    et al.
    Houis, S
    Gries, T
    Hilborn, J
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Adam, M
    Wurm, F. M.
    Suspension-adapted Chinese hamster ovary-derived cells expressing green fluorescent protein as a screening tool for biomaterials2009Ingår i: Biotechnology letters, ISSN 0141-5492, E-ISSN 1573-6776, Vol. 31, nr 8, s. 1143-1149Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Synthetic biomaterials play an important role in regenerative medicine. To be effective they must support cell attachment and proliferation in addition to being non-toxic and non-immunogenic. We used a suspension-adapted Chinese hamster ovary-derived cell line expressing green fluorescent protein (GFP) to assess cell attachment and growth on synthetic biomaterials by direct measurement of GFP-specific fluorescence. To simplify operations, all cell cultivation steps were performed in orbitally-shaken, disposable containers. Comparative studies between this GFP assay and previously established cell quantification assays demonstrated that this novel approach is suitable for rapid screening of a large number of samples. Furthermore the utility of our assay system was confirmed by evaluation of cell growth on three polyvinylidene fluoride polymer scaffolds that differed in pore diameter and drawing conditions. The data presented here prove the general utility of GFP-expressing cell lines and orbital shaking technology for the screening of biomaterials for tissue engineering applications.

  • 272. Engelhardt, Eva-Maria
    et al.
    Micol, Lionel A.
    Houis, Stephanie
    Wurm, Florian M.
    Hilborn, Jöns
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Polymerkemi.
    Hubbell, Jeffrey A.
    Frey, Peter
    A collagen-poly(lactic acid-co-epsilon-caprolactone) hybrid scaffold for bladder tissue regeneration2011Ingår i: Biomaterials, ISSN 0142-9612, E-ISSN 1878-5905, Vol. 32, nr 16, s. 3969-3976Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Scaffold materials should favor cell attachment and proliferation, and provide designable 3D structures with appropriate mechanical strength. Collagen matrices have proven to be beneficial scaffolds for tissue regeneration. However, apart from small intestinal submucosa, they offer a limited mechanical strength even if crosslinking can enhance their mechanical properties. A more cell-friendly way to increase material strength is to combine synthetic polymer meshes with plastic compressed collagen gels. This work describes the potential of plastic compressed collagen poly(lactic acid-co-epsilon-caprolactone) (PLAC) hybrids as scaffolds for bladder tissue regeneration. Human bladder smooth muscle and urothelial cells were cultured on and inside collagen PLAC hybrids in vitro. Scaffolds were analyzed by electron microscopy, histology, immunohistochemistry, and AlamarBlue assay. Both cell types proliferated in and on the hybrid, forming dense cell layers on top after two weeks. Furthermore, hybrids were implanted subcutaneously in the backs of nude mice. Host cell infiltration, scaffold degradation, and the presence of the seeded bladder cells were analyzed. Hybrids showed a lower inflammatory reaction in vivo than PLAC meshes alone, and first signs of polymer degradation were visible at six months. Collagen PLAC hybrids have potential for bladder tissue regeneration, as they show efficient cell seeding, proliferation, and good mechanical properties.

  • 273.
    Engelmark, Fredrik
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap. Institutionen för teknikvetenskaper, Elektronik. Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. Fysiska sektionen, Institutionen för fysik och materialvetenskap, Materialvetenskap. Fasta tillståndets elektronik.
    Iriarte, Gonzalo Fuentes
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap. Institutionen för teknikvetenskaper, Elektronik. Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. Fysiska sektionen, Institutionen för fysik och materialvetenskap, Materialvetenskap. Fasta tillståndets elektronik.
    Katardjiev, Ilia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap. Institutionen för teknikvetenskaper, Elektronik. Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. Fysiska sektionen, Institutionen för fysik och materialvetenskap, Materialvetenskap. Fasta tillståndets elektronik.
    Hårsta, Anders
    Institutionen för teknikvetenskaper, Elektronik. Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. Fysiska sektionen, Institutionen för fysik och materialvetenskap, Materialvetenskap. oorganisk kemi.
    Smith, Ulf
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap. Institutionen för teknikvetenskaper, Elektronik. Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. Fysiska sektionen, Institutionen för fysik och materialvetenskap, Materialvetenskap. Materialvetenskap.
    Berg, Sören
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap. Institutionen för teknikvetenskaper, Elektronik. Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. Fysiska sektionen, Institutionen för fysik och materialvetenskap, Materialvetenskap. Fasta tillståndets elektronik.
    Synthesis of highly oriented piezoelectric AlN films by reactive sputter deposition2000Ingår i: J. Vac. Sci. Technol. A, Vol. 18, nr 4, s. 1609-1612Artikel i tidskrift (Refereegranskat)
  • 274.
    Engelmark, Fredrik
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap. Institutionen för teknikvetenskaper, Elektronik. Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. Fasta tillståndets elektronik.
    Iriarte, Gonzalo Fuentes
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap. Institutionen för teknikvetenskaper, Elektronik. Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. Fasta tillståndets elektronik.
    Katardjiev, Ilia V
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap. Institutionen för teknikvetenskaper, Elektronik. Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. Fasta tillståndets elektronik.
    Ottosson, M
    Institutionen för teknikvetenskaper, Elektronik. Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. oorganisk kemi.
    Muralt, P
    Berg, Sören
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap. Institutionen för teknikvetenskaper, Elektronik. Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. Fasta tillståndets elektronik.
    Structural and electroacoustic studies of AIN thin films during low temperature radio frequency sputter deposition2001Ingår i: J Vac Sci Technol, Vol. A19, nr 5, s. 2664-2669Artikel i tidskrift (Refereegranskat)
  • 275. Engholm, M
    et al.
    Lashgari, Koroush
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. oorganisk kemi.
    Edvardsson, S
    Westin, Gunnar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. oorganisk kemi.
    Norin, L
    Atomically designed precursors in optical fiber amplifiers: The thermal stability of the heterobimetallic ErAl3(OPri)12 in a solution-coated silica soot2005Ingår i: Journal of Applied Physics, Vol. 97, s. 113104-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The thermal stability of the bimetallic alkoxide ErAl3(OPri)12 doped in an unsintered silica (soot) has been investigated. Samples have been heated to different temperatures (up to 1500 °C and analyzed by using ultraviolet-visible-near infrared absorption spectroscopy, infrared spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, thermal gravimetric analysis, and powder x-ray diffraction. It is seen that the doped samples heated up to 1000 °C show broad glasslike absorption spectra, indicating an amorphous structure, while the high-temperature sample shows an ordered crystallinelike structure with sharp characteristic absorption peaks. X-ray diffraction measurements indicate the formation of an ordered structure at temperatures of 1500 °C, revealing a crystal phase of silica and phases of erbium and aluminosilicate. A comparison is also made with a sample doped with aqueous ErCl3 and Al(NO3)3. It is concluded that the local structure of the ErAl3 precursor is not preserved at temperatures above 1000 °C. Alternative doping procedures are discussed.

  • 276. Engholm, M.
    et al.
    Norin, L.
    Edvardsson, S.
    Lashgari, K.
    Westin, Gunnar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    A structural investigation of a synthesized precursor for optical fiber applications: the heterobimetallic ErNb2(OPri)(13)2006Ingår i: Optical materials (Amsterdam), ISSN 0925-3467, E-ISSN 1873-1252, Vol. 29, nr 4, s. 386-391Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A structural investigation of a synthesized precursor in a silica glass matrix is performed. Silica soot samples are doped with the heterobimetallic precursor ErNb2(OPri)13 by using a conventional solution doping technique and heat treatments to different temperatures. The precursor has also been introduced into a silica fiber preform by using the modified chemical vapor deposition technique. Analyses are made by using ultraviolet–visible–near infrared absorption spectroscopy, scanning electron microscopy, energy dispersive spectroscopy and powder X-ray diffraction. It is concluded that an immiscible system of ErNbO4 crystallites and Nb2O5 is formed in the silica soot samples at high temperatures. Colloidal particles of ErNbO4 are also formed in the silica glass fiber preform showing interesting features.

  • 277. ENGQVIST, J
    et al.
    Jansson, Ulf
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. oorganisk kemi.
    INITIAL-STAGES OF GROWTH DURING CVD OF W ON TISI2 SUBSTRATES1995Ingår i: Thin Solid Films, Vol. 263, nr 1, s. 54-64Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The initial stages of growth in chemical vapour deposition (CVD) of W from WF6 have been studied in an ultra-high vacuum system using CVD TiSi2 films as substrates. The influence of different surface conditions on the substrate-reduction process was inve

  • 278.
    Engstrand, Johanna
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Designing star-like block-copolymers as compartmentalized nanostructures for drug delivery applications2010Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This thesis describes syntheses and characterization of star-like amphiphilic block copolymers consisting of poly(ethylene glycol) (PEG) as the hydrophilic block,polycarbonate as the hydrophobic block and an amine-containing dendrimer as the core molecule. The macromolecules were synthesized by either a convergent or adivergent approach that includes tandem click reactions and ring opening polymerizations (ROP) of methyl trimethyl carbonates (MTC) with differentfunctionalities. The ROP of MTC monomers was performed using organocatalysts that allow mild reaction condition and reasonable molecular weight distribution(PDI~1.3). These synthetic approaches provide the resultant polymers with three different conformations, which are; mikto-arm type, comb-block with short PEGbrushes, and linear block with long PEG chain. The star-like polymers that were synthesized were all water soluble and most of them formed nano aggregates inwater. Different morphologies were observed in AFM study depending on the polymer conformation. Interestingly, some of them had indications pointing towards alower critical solution temperature.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 279.
    Engstrand, Thomas
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Polymerkemi. polymerkemi.
    Aulin, Cecilia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Polymerkemi. polymerkemi.
    Hilborn, Jöns
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Polymerkemi. polymerkemi.
    The diverge effects of noggin on BMP-2 induced osteogenesis2007Ingår i: American society for bone and mineral research, Washington, 2007, 2007Konferensbidrag (Övrig (populärvetenskap, debatt, mm))
  • 280. Ensling, David
    et al.
    Kuezma, Mirjana
    Dominko, Robert
    Gustafsson, Torbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Thomas, Josh
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Gaberscek, Miran
    Combined SXPS and SXAS study of the electrochemical intercalation reaction of Li2NiTiO4 cathodes2009Ingår i: Lithium Battery Discussion Electrode Materials, Bordeaux-Arcachon, France, 20-25 September 2009, 2009, s. O39-Konferensbidrag (Refereegranskat)
  • 281.
    Ensling, David
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Stjerndahl, Mårten
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Nytén, Anton
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Gustafsson, Torbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Thomas, John O.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    A comparative XPS surface study of Li2FeSiO4/C cycled with LiTFSI- and LiPF6-based electrolytes2009Ingår i: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 19, s. 82-88Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    X-Ray photoelectron spectroscopy (XPS) has been used to characterise the surfaces of carbon-coated Li2FeSiO4 cathodes extracted from Li-ion batteries in both a charged and discharged state. 1 M lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) and lithium hexafluorophosphate (LiPF6) based electrolytes were used with ethylene carbonate (EC) and diethyl carbonate (DEC) as organic solvents. The LiTFSI-based electrolyte exhibited high salt stability and no significant formation of LiF. However, solvent reaction products from EC were found together with lithium carbonate. A LiPF6-based electrolyte, on the other hand, showed inferior salt stability with LixPFy, LixPOyFz and LiF species formed on the surface. Solvent reaction products together with lithium carbonate were also found. There are also indications that Li2FeSiO4 is degraded by the HF formed in the electrolyte by the hydrolysis of LiPF6. A better understanding of the surface chemistry of carbon-coated Li2FeSiO4 after the first cycles in a Li-ion battery has thus been achieved, thereby facilitating the optimisation of Li-ion batteries based on this potentially cheap and electrochemically most promising cathode material giving excellent capacity retention: <3% drop over 120 cycles.

  • 282. Ensling, David
    et al.
    Yuan, Jiang
    Gustafsson, Torbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Thomas, Josh
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Surface-film formation on Li2FeSiO4 cathodes for different electrolyte systems studies by XPS2009Ingår i: Lithium Battery Discussion Electrode Materials, Bordeaux-Arcachon, France, 20-25 September 2009, 2009, s. P30-Konferensbidrag (Refereegranskat)
  • 283.
    Eriksson, Rickard
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Gustafsson, Torbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    In situ diffraction studies of LiFePO4 under fast discharge2009Ingår i: Lithium Battery Discussion Electrode Materials, Bordeaux-Arcachon, France, 20-25 September 2009, 2009, s. P1-Konferensbidrag (Refereegranskat)
  • 284.
    Eriksson, Rickard
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Gustafsson, Torbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Dynamic Reduction of Crystallinity in LiFePO4 during Fast Cycling2009Konferensbidrag (Refereegranskat)
  • 285.
    Eriksson, S
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi. SOLID STATE PHYSICS.
    Mathieu, R
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Eriksen, P
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Rundlöf, Håkan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi. strukturkemi.
    Valkeapää, M
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    La1-xSrxMnO3 (0.33¡Üx¡Ü1) perovskites; A powder diffraction and magnetization study2002Ingår i: Ferroelectrics 270, 111Artikel i tidskrift (Refereegranskat)
  • 286.
    Eriksson, S-G
    et al.
    Uppsala universitet, Fakultetsövergripande enheter, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Neutronforskningslaboratoriet i Studsvik. Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Ivanov, S
    Eriksen, J
    Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Rundlöf, Håkan
    Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi. strukturkemi.
    McGreevy, R
    Berastegui, P
    Björnsson, P
    Rubhaussen, M
    Bäckström, J
    Käll, M
    Börjesson, L
    A neutron powder diffraction and inelastic light scattering study of (La,Sr)MnO32001Ingår i: Materials Science Forum, Vol. 378-381, s. 505-Artikel i tidskrift (Refereegranskat)
  • 287.
    Eriksson, SG
    et al.
    Uppsala universitet, Fakultetsövergripande enheter, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Neutronforskningslaboratoriet i Studsvik. Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Valkeapää, M
    Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Ivanov, S
    Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Eriksen, J
    Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Rundlöf, Håkan
    Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi. strukturkemi.
    Johansson, L-G
    Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Mathieu, R
    Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Svedlindh, P
    Tekniska sektionen, Institutionen för materialvetenskap. Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Bäckström, J
    Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Börjesson, L
    Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Phase transitions and magnetic order in La1-xSrxMnO3-d(x<0.3; 2.85<3-d<3.00)2002Ingår i: Ferroelectrics, Vol. 269, s. 309-314Artikel i tidskrift (Refereegranskat)
  • 288.
    Eriksson, T
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Andersson, A M
    Gejke, C
    Gustafsson, T
    Thomas, J O
    Temperature influence on the interface chemistry of LiMn2O4 electrodesIngår i: LangmuirArtikel i tidskrift (Refereegranskat)
  • 289.
    Eriksson, T
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Gustafsson, T
    Thomas, J O
    Surface structure on LiMn2O4 electrodesIngår i: Electrochem. Solid St. Lett.Artikel i tidskrift (Refereegranskat)
  • 290. Eriksson, T
    et al.
    Gustafsson, Torbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi. strukturkemi.
    Thomas, John
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi. strukturkemi.
    An XPS study of the SEI-Layer formed on a LixMn2O4 cathode1999Ingår i: Proc. Electrochem. Soc., Vol. 98, s. 315-Artikel i tidskrift (Refereegranskat)
  • 291.
    Eriksson, T
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Hjelm, A-K
    Lindberg, G
    Thomas, J O
    Gustafsson, T
    Kinetic investigation of LiMn2O4 cathodes by in situ XRD with constant current cycling and potential stepsIngår i: J. Electrochem. Soc.Artikel i tidskrift (Refereegranskat)
  • 292.
    Eriksson, Therese
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    The Structural Basis for Magnetic Order in New Manganese Compounds2005Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Materials with new or improved properties are crucial for technological development. To provide the foundation for future successful products, it is important to prepare and characterise new chemical compounds that could show unusual properties. The properties of magnetic materials are closely related to their crystal, magnetic and electronic structures. This thesis focuses on the novel synthesis and structural characterisation of a number of new ternary or pseudo-ternary silicides and germanides of manganese with iridium, cobalt or palladium. To provide a more complete picture of the complex magnetic properties, crystal and magnetic structure refinements by the Rietveld method of X-ray and neutron powder diffraction data are complemented by single-crystal X-ray diffraction, electron diffraction, magnetisation measurements and Reverse Monte Carlo simulations of magnetic short-range order. The experimental results are corroborated by first-principles electronic structure and total energy calculations.

    A commensurate non-collinear antiferromagnetic structure is found for most compounds of the solid solution Mn3Ir1-yCoySi1-xGex. The non-collinearity is a result of geometric frustration in a crystal structure with magnetic Mn atoms located on a three-dimensional network of triangles. The close structural similarity to the β-modification of elemental manganese, which does not order magnetically, inspired a closer theoretical comparison of the Mn3Ir1-yCoySi1-xGex propertieswith β-Mn.

    Magnetic frustration is also observed for Mn4Ir7-xMnxGe6, and is an important factor underlying the dramatic change from commensurate antiferromagnetic order to spin glass properties induced by a small variation in Mn concentration. Magnetic short-range order with dominant antiferromagnetic correlation is observed for Mn8Pd15Si7, and results from a random distribution of Mn atoms in-between the geometrically frustrated magnetic moments on the Mn octahedra.

    An incommensurate cycloidal magnetic structure, observed for IrMnSi, is stabilised by an electronic structure effect, which also accounts for the non-collinearity of the Mn3IrSi type magnetic structure.

    Delarbeten
    1. Cycloidal magnetic order in the compound IrMnSi
    Öppna denna publikation i ny flik eller fönster >>Cycloidal magnetic order in the compound IrMnSi
    Visa övriga...
    2005 (Engelska)Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 71, nr 17, s. 174420-Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    A new compound, IrMnSi, has been synthesized, and its crystal structure and magnetic properties have been investigated by means of neutron powder diffraction, magnetization measurements, and first-principles theory. The crystal structure is found to be of the TiNiSi type (ordered Co2P, space group Pnma). The Mn-projected electronic states are situated at the Fermi level, giving rise to metallic binding, whereas a certain degree of covalent character is observed for the chemical bond between the Ir and Si atoms. A cycloidal, i.e., noncollinear, magnetic structure was observed below 460 K, with the propagation vector q=[0,0,0.4530(5)] at 10 K. The magnetism is dominated by large moments on the Mn sites, 3.8μB∕atom from neutron diffraction. First-principles theory reproduces the propagation vector of the experimental magnetic structure as well as the angles between the Mn moments. The calculations further result in a magnetic moment of 3.2μB for the Mn atoms, whereas the Ir and Si moments are negligible, in agreement with observations. A calculation that more directly incorporates electron-electron interactions improves the agreement between the theoretical and experimental magnetic moments. A band mechanism is suggested to explain the observed magnetic order.

    Nationell ämneskategori
    Oorganisk kemi
    Identifikatorer
    urn:nbn:se:uu:diva-93494 (URN)10.1103/PhysRevB.71.174420 (DOI)
    Tillgänglig från: 2005-09-22 Skapad: 2005-09-22 Senast uppdaterad: 2020-03-31Bibliografiskt granskad
    2. From ordered antiferromagnet to spin glass: a new phase Mn4Ir7-xMnxGe6
    Öppna denna publikation i ny flik eller fönster >>From ordered antiferromagnet to spin glass: a new phase Mn4Ir7-xMnxGe6
    2005 Ingår i: Journal of Solid State Chemistry, ISSN 0022-4596, Vol. 178, s. 1495-1502Artikel i tidskrift (Refereegranskat) Published
    Identifikatorer
    urn:nbn:se:uu:diva-92908 (URN)
    Tillgänglig från: 2005-04-19 Skapad: 2005-04-19 Senast uppdaterad: 2013-03-21
    3. Crystal and magnetic structure of Mn3IrSi
    Öppna denna publikation i ny flik eller fönster >>Crystal and magnetic structure of Mn3IrSi
    Visa övriga...
    2004 (Engelska)Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 69, nr 5, s. 054422-Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    A new ternary Ir-Mn-Si phase with stoichiometry Mn3IrSi has been synthesized and found to crystallize in the cubic AlAu4-type structure, space group P213 with Z=4, which is an ordered form of the β-Mn structure. The unit cell dimension was determined by x-ray powder diffraction to a=6.4973(3)Å. In addition to the crystal structure, we have determined the magnetic structure and properties using superconducting quantum interference device magnetometry and Rietveld refinements of neutron powder diffraction data. A complex noncollinear magnetic structure is found, with magnetic moments of 2.97(4)μB at 10 K only on the Mn atoms. The crystal structure consists of a triangular network built up by Mn atoms, on which the moments are rotated 120° around the triangle axes. The magnetic unit cell is the same as the crystallographic and carries no net magnetic moment. The Néel temperature was determined to be 210 K. A first-principles study, based on density functional theory in a general noncollinear formulation, reproduces the experimental results with good agreement. The observed magnetic structure is argued to be the result of frustration of antiferromagnetic couplings by the triangular geometry.

    Nationell ämneskategori
    Materialteknik Oorganisk kemi Fysik
    Identifikatorer
    urn:nbn:se:uu:diva-93493 (URN)10.1103/PhysRevB.69.054422 (DOI)
    Tillgänglig från: 2005-09-22 Skapad: 2005-09-22 Senast uppdaterad: 2020-03-31Bibliografiskt granskad
    4. Structural and magnetic characterization of Mn3IrGe and Mn3Ir(Si1-xGex): experiments and theory
    Öppna denna publikation i ny flik eller fönster >>Structural and magnetic characterization of Mn3IrGe and Mn3Ir(Si1-xGex): experiments and theory
    Visa övriga...
    2004 (Engelska)Ingår i: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 177, nr 11, s. 4058-4066Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    The Structural and magnetic propertiesof a new ternary Ir-Mn-Ge phase, Mn3IrGe, as well as the solid solution Mn3Ir(Si1_xGex), O<x<1, have been investigated by means of X-ray and neutron powder diffraction, magnetization measurements and first principles calculations. The crystal structure is cubic, of the AlAu4-type (an ordered form of the ß-Mn structure), Z = 4. space group P213, and the unit-cell dimension varies linearly with the silicon content. For all compositions, antiferromagnetic

    ordering is found below a critical temperature of about 225 K. The magnetic structure is noncollinear, as a result of frustrated magnetic interactions on a triangular network of Mn atoms, on which the moments rotate 120° around the triangle axes. The magnitude of the magnetic moment at 10 K is 3.39(4) µB for Mn3IrGe. The theoretical calculations reproduce with very good accuracy the magnitudes as well as the directions of the experimentally observed magnetic moments.

    Nyckelord
    Manganese-iridium germanide, Manganese-indium silicide, Neutron diffraction, Rietveld method, Magnetic structure, Crystal structure, First principles calculations, Susceptibility measurements, Magnetic frustration
    Nationell ämneskategori
    Oorganisk kemi Materialteknik
    Identifikatorer
    urn:nbn:se:uu:diva-92910 (URN)10.1016/j.jssc.2004.07.001 (DOI)
    Tillgänglig från: 2005-04-19 Skapad: 2005-04-19 Senast uppdaterad: 2020-03-31Bibliografiskt granskad
    5. Magnetic properties of selected Mn-based transition metal compounds with β-Mn structure: Experiments and theory
    Öppna denna publikation i ny flik eller fönster >>Magnetic properties of selected Mn-based transition metal compounds with β-Mn structure: Experiments and theory
    Visa övriga...
    2005 Ingår i: Physical Review B, ISSN 1098-0121, Vol. 72, s. 144427-Artikel i tidskrift (Refereegranskat) Published
    Identifikatorer
    urn:nbn:se:uu:diva-92911 (URN)
    Tillgänglig från: 2005-04-19 Skapad: 2005-04-19 Senast uppdaterad: 2013-03-21
    6. Magnetic short-range order in the new ternary phase Mn8Pd15Si7
    Öppna denna publikation i ny flik eller fönster >>Magnetic short-range order in the new ternary phase Mn8Pd15Si7
    Visa övriga...
    2005 (Engelska)Ingår i: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 403, nr 1-2, s. 19-28Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    A new compound, Mn8Pd15Si7, is reported to crystallize in a face centered cubic unit cell of dimension a = 12.0141(2) Å, space group, and can thus be classified as a G-phase. The crystal structure was studied by single crystal X-ray diffraction, X-ray and neutron powder diffraction and electron diffraction. A filled Mg6Cu16Si7 type structure was found, corresponding to the Sc11Ir4 type structure. The magnetic properties were investigated by magnetization measurements and Reverse Monte Carlo modeling of low temperature magnetic short-range order (SRO). Dominating near neighbor antiferromagnetic correlations were found between the Mn atoms and geometric frustration in combination with random magnetic interactions via metal sites with partial Mn occupancy were suggested to hinder formation of long-range magnetic order.

    Nyckelord
    Intermetallics, Neutron powder diffraction, X-ray diffraction, Magnetic measurements
    Nationell ämneskategori
    Oorganisk kemi
    Identifikatorer
    urn:nbn:se:uu:diva-93495 (URN)10.1016/j.jallcom.2005.04.202 (DOI)
    Tillgänglig från: 2005-09-22 Skapad: 2005-09-22 Senast uppdaterad: 2017-12-14Bibliografiskt granskad
    Ladda ner fulltext (pdf)
    FULLTEXT01
    Ladda ner (pdf)
    COVER01
  • 293.
    Eriksson, Therese
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. oorganisk kemi.
    Bergqvist, L
    Fysiska sektionen, Fysiska institutionen. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Andersson, Yvonne
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. oorganisk kemi.
    Nordblad, P
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Fasta tillståndets fysik.
    Eriksson, O
    Fysiska sektionen, Fysiska institutionen. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Magnetic properties of selected Mn-based transition metal compounds with β-Mn structure: Experiments and theory2005Ingår i: Physical Review B, Vol. 72, s. 144427-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Two compounds, Mn3CoSi and Mn3CoGe have been synthesized and found to crystallize in the AlAu4 type structure, an ordered form of the β-Mn structure. The magnetic structure and properties have been studied by magnetometry and neutron powder diffraction and the theoretical work is based on first principles total energy calculations. Comparison is made with the magnetic properties of the isostructural compounds Mn3IrGe and Mn3IrSi. The solid solutions Mn3Ir1–yCoySi (0y1) and Mn3CoSi1–xGex (0x1) are also studied. A noncollinear antiferromagnetic structure is experimentally observed for y=0.20 as well as for x=0.50 and 1.0, similar to that of Mn3IrSi and Mn3IrGe, with 120° angles between magnetic moments on a triangular network of Mn atoms, and this finding is corroborated by theoretical calculations. For y=0.80–1.0 a transformation to a new type of magnetic structure takes place. The magnetic transition temperature decreases on decreasing unit cell dimension, with good qualitative agreement with the decay of the calculated interatomic exchange energy. Both theory and experiments find the magnitude of the Mn magnetic moment to decrease on decreasing unit cell volume, the same trend is found in calculations for β-Mn.

  • 294.
    Eriksson, Therese
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Bergqvist, Lars
    Andersson, Yvonne
    Nordblad, Per
    Eriksson, Olle
    Magnetic properties of selected Mn-based transition metal compounds with β-Mn structure: Experiments and theory2005Ingår i: Physical Review B, ISSN 1098-0121, Vol. 72, s. 144427-Artikel i tidskrift (Refereegranskat)
  • 295.
    Eriksson, Therese
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Bergqvist, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen.
    Burkert, Till
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen.
    Felton, Solveig
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper.
    Tellgren, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper.
    Eriksson, Olle
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen.
    Andersson, Yvonne
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Cycloidal magnetic order in the compound IrMnSi2005Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 71, nr 17, s. 174420-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A new compound, IrMnSi, has been synthesized, and its crystal structure and magnetic properties have been investigated by means of neutron powder diffraction, magnetization measurements, and first-principles theory. The crystal structure is found to be of the TiNiSi type (ordered Co2P, space group Pnma). The Mn-projected electronic states are situated at the Fermi level, giving rise to metallic binding, whereas a certain degree of covalent character is observed for the chemical bond between the Ir and Si atoms. A cycloidal, i.e., noncollinear, magnetic structure was observed below 460 K, with the propagation vector q=[0,0,0.4530(5)] at 10 K. The magnetism is dominated by large moments on the Mn sites, 3.8μB∕atom from neutron diffraction. First-principles theory reproduces the propagation vector of the experimental magnetic structure as well as the angles between the Mn moments. The calculations further result in a magnetic moment of 3.2μB for the Mn atoms, whereas the Ir and Si moments are negligible, in agreement with observations. A calculation that more directly incorporates electron-electron interactions improves the agreement between the theoretical and experimental magnetic moments. A band mechanism is suggested to explain the observed magnetic order.

  • 296.
    Eriksson, Therese
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    Bergqvist, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Teoretisk magnetism.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap.
    Eriksson, Olle
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Teoretisk magnetism.
    Andersson, Yvonne
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    Structural and magnetic characterization of Mn3IrGe and Mn3Ir(Si1-xGex): experiments and theory2004Ingår i: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 177, nr 11, s. 4058-4066Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Structural and magnetic propertiesof a new ternary Ir-Mn-Ge phase, Mn3IrGe, as well as the solid solution Mn3Ir(Si1_xGex), O<x<1, have been investigated by means of X-ray and neutron powder diffraction, magnetization measurements and first principles calculations. The crystal structure is cubic, of the AlAu4-type (an ordered form of the ß-Mn structure), Z = 4. space group P213, and the unit-cell dimension varies linearly with the silicon content. For all compositions, antiferromagnetic

    ordering is found below a critical temperature of about 225 K. The magnetic structure is noncollinear, as a result of frustrated magnetic interactions on a triangular network of Mn atoms, on which the moments rotate 120° around the triangle axes. The magnitude of the magnetic moment at 10 K is 3.39(4) µB for Mn3IrGe. The theoretical calculations reproduce with very good accuracy the magnitudes as well as the directions of the experimentally observed magnetic moments.

  • 297.
    Eriksson, Therese
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Fysiska sektionen, Institutionen för fysik och materialvetenskap, Fysik IV. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. oorganisk kemi.
    Eriksson, Olle
    Fysiska institutionen. Fysiska institutionen. Fysiska sektionen, Institutionen för fysik och materialvetenskap, Fysik IV. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. teoretisk magnetism.
    On the Magnetic and Crystalline Structure of Mn3IrSi2004Ingår i: phys rev b, Vol. 69, s. 54422-Artikel i tidskrift (Refereegranskat)
  • 298.
    Eriksson, Therese
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Fysiska sektionen, Institutionen för fysik och materialvetenskap, Fysik IV. oorganisk kemi.
    Felton, Solveig
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Fysiska sektionen, Institutionen för fysik och materialvetenskap, Fysik IV. Fasta tillståndets fysik.
    Lizárraga, Raquel
    Fysiska institutionen. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Fysiska sektionen, Institutionen för fysik och materialvetenskap, Fysik IV.
    Eriksson, Olle
    Fysiska institutionen. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Fysiska sektionen, Institutionen för fysik och materialvetenskap, Fysik IV.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Fysiska sektionen, Institutionen för fysik och materialvetenskap, Fysik IV. Fasta tillståndets fysik.
    Andersson, Yvonne
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Fysiska sektionen, Institutionen för fysik och materialvetenskap, Fysik IV. oorganisk kemi.
    Crystal structure and magnetic properties of the new phase Mn3IrSi2004Ingår i: Journal of Magnetism and Magnetic Materials, nr 272-276, s. 823-825Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A new phase in the ternary Ir–Mn–Si system has been synthesised. From powder neutron diffraction data the crystal structure was determined to be of the AlAu4 type and to be described in the cubic space group P213 with the unit cell a=6.4973(3) Å. Susceptibility measurements using a SQUID-magnetometer showed a transition typical of antiferromagnetism, with TN=210 K. Low temperature antiferromagnetic order is confirmed by extra peaks in neutron diffractograms recorded at 10 and 80 K.

  • 299.
    Eriksson, Therese
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    Lizárraga, Raquel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Teoretisk magnetism.
    Felton, Solveig
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap.
    Bergqvist, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Teoretisk magnetism.
    Andersson, Yvonne
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap.
    Eriksson, Olle
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Teoretisk magnetism.
    Crystal and magnetic structure of Mn3IrSi2004Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 69, nr 5, s. 054422-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A new ternary Ir-Mn-Si phase with stoichiometry Mn3IrSi has been synthesized and found to crystallize in the cubic AlAu4-type structure, space group P213 with Z=4, which is an ordered form of the β-Mn structure. The unit cell dimension was determined by x-ray powder diffraction to a=6.4973(3)Å. In addition to the crystal structure, we have determined the magnetic structure and properties using superconducting quantum interference device magnetometry and Rietveld refinements of neutron powder diffraction data. A complex noncollinear magnetic structure is found, with magnetic moments of 2.97(4)μB at 10 K only on the Mn atoms. The crystal structure consists of a triangular network built up by Mn atoms, on which the moments are rotated 120° around the triangle axes. The magnetic unit cell is the same as the crystallographic and carries no net magnetic moment. The Néel temperature was determined to be 210 K. A first-principles study, based on density functional theory in a general noncollinear formulation, reproduces the experimental results with good agreement. The observed magnetic structure is argued to be the result of frustration of antiferromagnetic couplings by the triangular geometry.

  • 300.
    Eriksson, Therese
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Mellergård, Anders
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper.
    Larsson, Anna-Kristin
    Felton, Solveig
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper.
    Höwing, Jonas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Gustafsson, Torbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Andersson, Yvonne
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Magnetic short-range order in the new ternary phase Mn8Pd15Si72005Ingår i: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 403, nr 1-2, s. 19-28Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A new compound, Mn8Pd15Si7, is reported to crystallize in a face centered cubic unit cell of dimension a = 12.0141(2) Å, space group, and can thus be classified as a G-phase. The crystal structure was studied by single crystal X-ray diffraction, X-ray and neutron powder diffraction and electron diffraction. A filled Mg6Cu16Si7 type structure was found, corresponding to the Sc11Ir4 type structure. The magnetic properties were investigated by magnetization measurements and Reverse Monte Carlo modeling of low temperature magnetic short-range order (SRO). Dominating near neighbor antiferromagnetic correlations were found between the Mn atoms and geometric frustration in combination with random magnetic interactions via metal sites with partial Mn occupancy were suggested to hinder formation of long-range magnetic order.

3456789 251 - 300 av 1425
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf