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  • 1.
    Berglund, Sigrid
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Bassy, Clara
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Kaya, Ibrahim
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Andrén, Per E.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, MMS, Medical Mass Spectrometry. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Shtender, Vitalii
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Lasagna, Mauricio
    Department of Biochemistry and Biphysics, Texas A&M University.
    Tommos, Cecilia
    Department of Biochemistry and Biphysics, Texas A&M University.
    Magnuson, Ann
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Molecular Biomimetics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Chemical Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Molecular Biomimetics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Glover, Starla
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Hydrogen production by a fully de novo enzyme2024Manuscript (preprint) (Other academic)
    Abstract [en]

    Molecular catalysts based on abundant elements that function in neutral water represent an essential component of sustainable hydrogen production. Artificial hydrogenases based on protein-inorganic hybrids have emerged as an intriguing class of catalysts for this purpose. We have prepared a novel artificial hydrogenase based on cobaloxime bound to a de novo three alpha-helical protein, α3C, via a pyridyl-based unnatural amino acid. The functionalized de novo protein was characterised by UV-visible, CD, and EPR spectroscopy, as well as MALDI spectrometry, which confirmed the presence and ligation of cobaloxime to the protein. The new de novo protein produced hydrogen under electrochemical, photochemical and reductive chemical conditions in neutral water solution. A change in hydrogen evolution capability of the de novo enzyme compared with native cobaloxime was observed, with turnover numbers around 80% of that of cobaloxime, and hydrogen evolution rates of 40% of that of cobaloxime. We discuss these findings in the context of existing literature, how our study contributes important information about the functionality of cobaloxime as hydrogen evolving catalysts in protein environments, and the feasibility of using de novo proteins for developent into artificial metalloenzymes. Small de novo proteins as enzyme scaffolds have the potential to function as upscalable bioinspired catalysts thanks to their efficient atom economy, and the findings presented here show that these types of novel enzymes are a possible product. 

  • 2.
    Borisov, Vladislav
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Xu, Qichen
    KTH Royal Inst Technol, AlbaNova Univ Ctr, Sch Engn Sci, Dept Appl Phys, SE-10691 Stockholm, Sweden.;KTH Royal Inst Technol, SeRC Swedish Sci Res Ctr, SE-10044 Stockholm, Sweden..
    Ntallis, Nikolaos
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Clulow, Rebecca
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Shtender, Vitalii
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Cedervall, Johan
    Stockholm Univ, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden..
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Wikfeldt, Kjartan Thor
    KTH Royal Inst Technol, PDC Ctr High Performance Comp, SE-10044 Stockholm, Sweden..
    Thonig, Danny
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Örebro Univ, Sch Sci & Technol, SE-70182 Örebro, Sweden..
    Pereiro, Manuel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Bergman, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Delin, Anna
    KTH Royal Inst Technol, AlbaNova Univ Ctr, Sch Engn Sci, Dept Appl Phys, SE-10691 Stockholm, Sweden.;KTH Royal Inst Technol, SeRC Swedish Sci Res Ctr, SE-10044 Stockholm, Sweden..
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Örebro Univ, Sch Sci & Technol, SE-70182 Örebro, Sweden..
    Tuning skyrmions in B20 compounds by 4d and 5d doping2022In: Physical Review Materials, E-ISSN 2475-9953, Vol. 6, no 8, article id 084401Article in journal (Refereed)
    Abstract [en]

    Skyrmion stabilization in novel magnetic systems with the B20 crystal structure is reported here, primarily based on theoretical results. The focus is on the effect of alloying on the 3d sublattice of the B20 structure by substitution of heavier 4d and 5d elements, with the ambition to tune the spin-orbit coupling and its influence on magnetic interactions. State-of-the-art methods based on density functional theory are used to calculate both isotropic and anisotropic exchange interactions. Significant enhancement of the Dzyaloshinskii-Moriya interaction is reported for 5d-doped FeSi and CoSi, accompanied by a large modification of the spin stiffness and spiralization. Micromagnetic simulations coupled to atomistic spin-dynamics and ab initio magnetic interactions reveal the spin-spiral nature of the magnetic ground state and field-induced skyrmions for all these systems. Especially small skyrmions similar to 50 nm are predicted for Co0.75Os0.25Si, compared to similar to 148 nm for Fe0.75Co0.25Si. Convex-hull analysis suggests that all B20 compounds considered here are structurally stable at elevated temperatures and should be possible to synthesize. This prediction is confirmed experimentally by synthesis and structural analysis of the Ru-doped CoSi systems discussed here, both in powder and in single-crystal forms.

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  • 3.
    Czub, J.
    et al.
    AGH Univ Sci & Technol, Fac Phys & Appl Comp Sci, Mickiewicza 30, PL-30059 Krakow, Poland.
    Shtender, Vitalii
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Przewoznik, J.
    AGH Univ Sci & Technol, Fac Phys & Appl Comp Sci, Mickiewicza 30, PL-30059 Krakow, Poland.
    Zarzecka, A.
    AGH Univ Sci & Technol, Fac Phys & Appl Comp Sci, Mickiewicza 30, PL-30059 Krakow, Poland.
    Hoser, A.
    Helmholtz Zentrum Berlin, Hahn Meitner Pl 1, D-14109 Berlin, Germany.
    Gondek, L.
    AGH Univ Sci & Technol, Fac Phys & Appl Comp Sci, Mickiewicza 30, PL-30059 Krakow, Poland.
    On the properties of the novel CeMgNi2T2 (T = Co, Cu) alloys and their hydrides2020In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 814, article id 152244Article in journal (Refereed)
    Abstract [en]

    In this contribution, we report the results of the studies on the novel CeMgNi2Co2 and CeMgNi2Cu2 alloys and their hydrides/deuterides. Both the parent alloys and the CeMgNi2Co2H6.1 hydride crystallize in the MgCu4Sn-type structure, while the CeMgNi2Cu2H6.0 hydride becomes almost completely amorphous. In the MgCu4Sn structure the 3d metals are distributed over the 16e site forming the pyrochlore lattice. That makes this system particularly interesting as concerns the magnetic properties. Our studies reveal that magnetic susceptibilities of the alloys are weakly temperature-dependent and therefore, the Pauli-like paramagnetism can be suggested. Additionally, the results of the low temperature neutron diffraction experiments revealed the lack of the long-range magnetic ordering.

  • 4.
    Dey, Ananta
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Mendalz, Amal
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Wach, Anna
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland.;Jagiellonian Univ, SOLARIS Natl Synchrotron Radiat Ctr, Krakow, Poland..
    Vadell, Robert Bericat
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Silveira, Vitor
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Leidinger, Paul Maurice
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland..
    Huthwelker, Thomas
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland..
    Shtender, Vitalii
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Novotny, Zbynek
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland..
    Artiglia, Luca
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland..
    Sá, Jacinto
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Polish Acad Sci, Inst Phys Chem, Marcina Kasprzaka 44-52, PL-01224 Warsaw, Poland..
    Hydrogen evolution with hot electrons on a plasmonic-molecular catalyst hybrid system2024In: Nature Communications, E-ISSN 2041-1723, Vol. 15, article id 445Article in journal (Refereed)
    Abstract [en]

    Plasmonic systems convert light into electrical charges and heat, mediating catalytic transformations. However, there is ongoing controversy regarding the involvement of hot carriers in the catalytic process. In this study, we demonstrate the direct utilisation of plasmon hot electrons in the hydrogen evolution reaction with visible light. We intentionally assemble a plasmonic nanohybrid system comprising NiO/Au/[Co(1,10-Phenanthrolin-5-amine)2(H2O)2], which is unstable at water thermolysis temperatures. This assembly limits the plasmon thermal contribution while ensuring that hot carriers are the primary contributors to the catalytic process. By combining photoelectrocatalysis with advanced in situ spectroscopies, we can substantiate a reaction mechanism in which plasmon-induced hot electrons play a crucial role. These plasmonic hot electrons are directed into phenanthroline ligands, facilitating the rapid, concerted proton-electron transfer steps essential for hydrogen generation. The catalytic response to light modulation aligns with the distinctive profile of a hot carrier-mediated process, featuring a positive, though non-essential, heat contribution. Direct participation of plasmon-induced hot electrons in the photoelectrocatalytic synthesis of hydrogen. This report solves a long-lasting contentious issue surrounding plasmonic materials on catalytic applications.

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  • 5.
    Dey, Ananta
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Silveira, Vitor R.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Bericat Vadell, Robert
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Lindblad, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Lindblad, Rebecka
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Shtender, Vitalii
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Görlin, Mikaela
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Sá, Jacinto
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Polish Acad Sci, Inst Phys Chem, Marcina Kasprzaka 44-52, PL-01224 Warsaw, Poland.
    Exploiting hot electrons from a plasmon nanohybrid system for the photoelectroreduction of CO22024In: Communications Chemistry, E-ISSN 2399-3669, Vol. 7, no 1, article id 59Article in journal (Refereed)
    Abstract [en]

    Plasmonic materials convert light into hot carriers and heat to mediate catalytic transformation. The participation of hot carriers (photocatalysis) remains a subject of vigorous debate, often argued on the basis that carriers have ultrashort lifetime incompatible with drive photochemical processes. This study utilises plasmon hot electrons directly in the photoelectrocatalytic reduction of CO2 to CO via a Ppasmonic nanohybrid. Through the deliberate construction of a plasmonic nanohybrid system comprising NiO/Au/ReI(phen-NH2)(CO)3Cl (phen-NH2 = 1,10-Phenanthrolin-5-amine) that is unstable above 580 K; it was possible to demonstrate hot electrons are the main culprit in CO2 reduction. The engagement of hot electrons in the catalytic process is derived from many approaches that cover the processes in real-time, from ultrafast charge generation and separation to catalysis occurring on the minute scale. Unbiased in situ FTIR spectroscopy confirmed the stepwise reduction of the catalytic system. This, coupled with the low thermal stability of the ReI(phen-NH2)(CO)3Cl complex, explicitly establishes plasmonic hot carriers as the primary contributors to the process. Therefore, mediating catalytic reactions by plasmon hot carriers is feasible and holds promise for further exploration. Plasmonic nanohybrid systems can leverage plasmon’s unique photophysics and capabilities because they expedite the carrier’s lifetime.

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  • 6.
    Ghorai, Sagar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Cedervall, Johan
    Clulow, Rebecca
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Huang, Shuo
    Ericsson, Tore
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Häggström, Lennart
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Shtender, Vitalii
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Delczeg-Czirjak, Erna K.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Vitos, Levente
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Site-specific atomic substitution in a giant magnetocaloric Fe2P-type system2023In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 107, no 10, article id 104409Article in journal (Refereed)
    Abstract [en]

    Giant magnetocaloric (GMC) materials constitute a requirement for near room temperature magnetic refrigeration. (Fe,Mn)2(P,Si) is a GMC compound with strong magnetoelastic coupling. The main hindrance towards application of this material is a comparably large temperature hysteresis, which can be reduced by metal site substitution with a nonmagnetic element. However, the (Fe,Mn)2(P,Si) compound has two equally populated metal sites, the tetrahedrally coordinated 3f and the pyramidally coordinated 3g sites. The magnetic and magnetocaloric properties of such compounds are highly sensitive to the site specific occupancy of the magnetic atoms. Here we have attempted to study separately the effect of 3f and 3g site substitution with equal amounts of vanadium. Using formation energy calculations, the site preference of vanadium and its influence on the magnetic phase formation are described. A large difference in the isothermal entropy change (as high as 44\%) with substitution in the 3f and 3g sites is observed. The role of the lattice parameter change with temperature and the strength of the magnetoelastic coupling on the magnetic properties are highlighted.

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    fulltext
  • 7.
    Ghorai, Sagar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Cedervall, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Huang, Shuo
    Clulow, Rebecca
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Ericsson, Tore
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Häggström, Lennart
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Skini, Ridha
    Shtender, Vitalii
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Delczeg-Czirjak, Erna Krisztina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Vitos, Levente
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Magnetocaloric properties of nonstoichiometric Fe2P-type intermetallics near room temperatureManuscript (preprint) (Other academic)
  • 8.
    Ghorai, Sagar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Shtender, Vitalii
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Delczeg-Czirjak, Erna Krisztina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Vieira, Rafael Martinho
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Herper, Heike C.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Magneto-structural coupling strength dependent giant magnetocaloric effect in (Mn,Fe)NiSi-systemManuscript (preprint) (Other academic)
  • 9.
    Ghorai, Sagar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Shtender, Vitalii
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Ström, Petter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Skini, Ridha
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Effect of small cation occupancy and anomalous Griffiths phase disorder in nonstoichiometric magnetic perovskites2022In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 895, article id 162714Article in journal (Refereed)
    Abstract [en]

    The structural, magnetic, magnetocaloric and Griffiths phase (GP) disorder of non-stoichiometric perovskite manganites La0.8-xSr0.2-yMn1+x+yO3 are reported here. Determination of valence states and structural phases evidenced that the smaller cations Mn2+ and Mn3+ will not occupy the A-site of a perovskite under atmospheric synthesis conditions. The same analysis also supports that the vacancy in the A-site of a perovskite induces a similar vacancy in the B-site. The La3+ and Sr2+ cation substitutions in the A-site with vacancy influences the magnetic phase transition temperature (TC) inversely, which is explained in terms of the electronic bandwidth change. An anomalous non-linear change of the GP has been observed in the Sr substituted compounds. The agglomeration of Mn3+-Mn4+ pairs (denoted as dimerons), into small ferromagnetic clusters, has been identified as the reason for the occurrence of the GP. A threshold limit of the dimeron formation explains the observed non-linear behaviour of the GP formation. The Sr-substituted compounds show a relatively large value of isothermal entropy change (maximum 3.27 J/kgK at mu H-0 = 2T) owing to its sharp magnetic transition, while the broad change of magnetization in the La-substituted compound enhances the relative cooling power (maximum 98 J/kg at mu H-0 = 2T).

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  • 10.
    Ghorai, Sagar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Vieira, Rafael Martinho
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Shtender, Vitalii
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Delczeg-Czirjak, Erna Krisztina
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Herper, Heike C.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Björkman, Torbjörn
    Simak, Sergei I.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Theoretical Magnetism. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Experimental Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics I. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics IV. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Condensed Matter Theory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Materials Theory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Structural Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Surface Biotechnology. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics IV. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Structural Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Theoretical Magnetism. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Materials Science. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Experimental Physics. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Giant magnetocaloric effect in the (Mn,Fe)NiSi-system2023Manuscript (preprint) (Other academic)
    Abstract [en]

    The search for energy-efficient and environmentally friendly cooling technologies is a key driver for the development of magnetic refrigeration based on the magnetocaloric effect (MCE). This phenomenon arises from the interplay between magnetic and lattice degrees of freedom that is strong in certain materials, leading to a change in temperature upon application or removal of a magnetic field. Here we report on a new material, Mn1−xFexNiSi0.95Al0.05, with an exceptionally large isothermal entropy at room temperature. By combining experimental and theoretical methods we outline the microscopic mechanism behind the large MCE in this material. It is demonstrated that the competition between the Ni2In-type hexagonal phase and the MnNiSi-type orthorhombic phase, that coexist in this system, combined with the distinctly different magnetic properties of these phases, is a key parameter for the functionality of this material for magnetic cooling.

  • 11.
    Grilli, Davide
    et al.
    Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden.;Univ Genoa, Dept Chem & Ind Chem, DCCI, I-16146 Genoa, Italy.;Inst SPIN CNR, I-16152 Genoa, Italy..
    Smetana, Volodymyr
    Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden.;Dept Biol & Chem Engn, DK-8000 Aarhus C, Denmark.;iNANO, DK-8000 Aarhus C, Denmark..
    Ahmed, Sheikh J.
    Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden.;Dept Biol & Chem Engn, DK-8000 Aarhus C, Denmark.;iNANO, DK-8000 Aarhus C, Denmark..
    Shtender, Vitalii
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Pani, Marcella
    Univ Genoa, Dept Chem & Ind Chem, DCCI, I-16146 Genoa, Italy.;Inst SPIN CNR, I-16152 Genoa, Italy..
    Manfrinetti, Pietro
    Univ Genoa, Dept Chem & Ind Chem, DCCI, I-16146 Genoa, Italy.;Inst SPIN CNR, I-16152 Genoa, Italy..
    Mudring, Anja-Verena
    Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden.;Dept Biol & Chem Engn, DK-8000 Aarhus C, Denmark.;iNANO, DK-8000 Aarhus C, Denmark..
    Lan(n+1)+xNin(n+5)+ySi(n+1)(n+2)–z: A Symmetric Mirror Homologous Series in the La-Ni-Si System2023In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 62, no 27, p. 10736-10742Article in journal (Refereed)
    Abstract [en]

    A homologous series La n(n+1)+x Ni n(n+5)+y Si(n+1)(n+2)-z has beenobserved inthe La-Ni-Si representing a symmetric Ni-rich mirrorto the La(n+1)(n+2)Ni n(n-1)+2Si n(n+1). A series of fourhomologous silicides have been discovered duringsystematic explorations in the central part of the La-Ni-Sisystem at 1000 & DEG;C. All compounds La12.5Ni28.0Si18.3 (n = 3; a = 28.8686(8), c = 4.0737(2) & ANGS;, Z = 3), La22.1Ni39.0Si27.8 (n = 4; a = 20.9340(6), c = 4.1245(2) & ANGS;, Z = 1), La32.9Ni49.8Si39.3 (n = 5; a = 24.946(1), c = 4.1471(5) & ANGS;, Z = 1), and La44.8Ni66.1Si53.4 (n =6; a = 28.995(5), c = 4.158(1) & ANGS;, Z = 1) crystallize in the hexagonal space group P6(3)/m and can be generalizedaccording to La n(n+1)+x Ni n(n+5)+y Si(n+1)(n+2)-z with n = 3-6. Their crystalstructures are based on AlB2-type building blocks, fusedLa-centered Ni6Si6 hexagonal prisms, yieldinglarger oligomeric equilateral domains with the edge size equal to n. The domains extend along the c axisand show checkered ordering of the cationic and anionic parts, whileall their atoms are located on mirror planes. La n(n+1)+x Ni n(n+5)+y Si(n+1)(n+2)-z can beconsidered as a mirror series to the La-rich La(n+1)(n+2)Ni n(n-1)+2Si n(n+1), where an exchange of the formal cationic and anionic sites,i.e., La and Si, occurs. The La-Ni-Si system is thefirst system where two such analogous series have been observed.

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  • 12.
    Hedlund, Daniel
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Rosenqvist Larsen, Simon
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Shtender, Vitalii
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Influence of Mn content on the magnetic properties of the hexagonal Mn (Co,Ge)2 phase2023In: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 233, article id 115534Article in journal (Refereed)
    Abstract [en]

    Herein, we report on the effect of Mn content on the magnetic properties of the hexagonal Mn(Co,Ge)2 with composition Mn36+xCo49-xGe15.This compound was previously described as Mn2Co3Ge (MgZn2-type structure), but later as Mn(Co,Ge)2 with its own structure type, all samples in this work follow the same superstructure model. Samples were synthesized by induction melting, the crystal structures were evaluated using a combination of X-ray diffraction together with scanning electron microscopy equipped and an energy dispersive X-ray spectroscopy detector. The Curie temperature (TC) is shifted towards lower temperature as the Mn content is increased. On the other hand, the spin reorientation temperature (TSRT) increases and the magnetic moment decreases as the Mn content is increased. The magnetocaloric properties were investigated for the x = 1 alloy, Mn37Co48Ge15. It was found that the isothermal entropy change is 2 J kg−1 K−1 at room temperature for an applied field of 5 T.

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  • 13.
    Larsen, Simon R.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Shtender, Vitalii
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Hedlund, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Delczeg-Czirjak, Erna K.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Beran, Premysl
    Nuclear Physics Institute, ASCR, Hlavni 130, 25068 Rez, Czech Republic; European Spallation Source ESS ERIC, Box 176, 221 00, Lund, Sweden.
    Cedervall, Johan
    Department of Materials and Environmental Chemistry, Stockholm University, 10691 Stockholm, Sweden.
    Vishina, Alena
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Hansen, Thomas C.
    Institut Laue-Langevin, 71 avenue des Martyrs, 38000 Grenoble, France.
    Herper, Heike C.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. School of Science and Technology, Örebro University, SE-701 82 Örebro, Sweden.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Revealing the Magnetic Structure and Properties of Mn(Co,Ge)22022In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 61, no 44, p. 17673-17681Article in journal (Refereed)
    Abstract [en]

    The atomic and magnetic structures of Mn(Co,Ge)2 are reported herein. The system crystallizes in the space group P63/mmc as a superstructure of the MgZn2-type structure. The system exhibits two magnetic transitions with associated magnetic structures, a ferromagnetic (FM) structure around room temperature, and an incommensurate structure at lower temperatures. The FM structure, occurring between 193 and 329 K, is found to be a member of the magnetic space group P63/mmc′. The incommensurate structure found below 193 K is helical with propagation vector k = (0 0 0.0483). Crystallographic results are corroborated by magnetic measurements and ab initio calculations.

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  • 14.
    Mansouri, Moufida
    et al.
    Chalmers Univ Technol, Dept Chem & Chem Engn Nucl Chem & Ind Mat Recyclin, S-41296 Gothenburg, Sweden..
    Shtender, Vitalii
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Tunsu, Cristian
    Chalmers Univ Technol, Dept Chem & Chem Engn Nucl Chem & Ind Mat Recyclin, S-41296 Gothenburg, Sweden..
    Yilmaz, Duygu
    Chalmers Univ Technol, Dept Chem & Chem Engn, S-41296 Gothenburg, Sweden..
    Messaoudi, Olfa
    Hail Univ, Dept Phys, Hail, Saudi Arabia..
    Ebin, Burcak
    Chalmers Univ Technol, Dept Chem & Chem Engn Nucl Chem & Ind Mat Recyclin, S-41296 Gothenburg, Sweden..
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Petranikova, Martina
    Chalmers Univ Technol, Dept Chem & Chem Engn Nucl Chem & Ind Mat Recyclin, S-41296 Gothenburg, Sweden..
    Production of AB5 materials from spent Ni-MH batteries with further tests of hydrogen storage suitability2022In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 539, article id 231459Article in journal (Refereed)
    Abstract [en]

    A novel approach for the reuse of rare earth (REE) elements generated during hydrometallurgical processing of Ni-MH batteries as alternative sources is provided to valorize Ni-MH batteries wastes. The production of AB5-based alloys from spent Ni-MH waste was thoroughly investigated. The REE elements were recovered as a mixture in oxalate form and annealed at 900 °C to obtain a single-phase REEs oxide REE2O3. Citrate gel and glycine nitrate processes followed by the Ca reduction process under H2 atmosphere were used to produce the AB5 alloys. The alloys were successfully produced, and their crystal structure and morphology have been studied using X-ray diffraction (XRD), scanning electron microscopy (SEM) with supporting energy-dispersive X-ray (EDS) analysis. Nanoparticles with a size of 173±3 nm and 150±8 nm were observed using transmission electron microscopy (TEM) for CG and GNP alloys. Studied samples were subjected to hydrogenation, and the structural changes were depicted.

  • 15.
    Pani, Marcella
    et al.
    Univ Genoa, Dept Chem & Ind Chem, DCCI, Via Dodecaneso 31, I-16146 Genoa, Italy.;CNR SPIN, Corso Perrone 24, I-16152 Genoa, Italy..
    Provino, Alessia
    Univ Genoa, Dept Chem & Ind Chem, DCCI, Via Dodecaneso 31, I-16146 Genoa, Italy.;CNR SPIN, Corso Perrone 24, I-16152 Genoa, Italy..
    Smetana, Volodymyr
    Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden..
    Shtender, Vitalii
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Bernini, Cristina
    CNR SPIN, Corso Perrone 24, I-16152 Genoa, Italy..
    Mudring, Anja-Verena
    Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden.;253 Aarhus Univ, Dept Chem, DK-8000 Aarhus C, Denmark.;253 Aarhus Univ, iNANO, DK-8000 Aarhus C, Denmark..
    Manfrinetti, Pietro
    Univ Genoa, Dept Chem & Ind Chem, DCCI, Via Dodecaneso 31, I-16146 Genoa, Italy.;CNR SPIN, Corso Perrone 24, I-16152 Genoa, Italy..
    Four ternary silicides in the La-Ni-Si system: from polyanionic layers to frameworks2022In: CrystEngComm, ISSN 1466-8033, E-ISSN 1466-8033, Vol. 24, no 47, p. 8219-8228Article in journal (Refereed)
    Abstract [en]

    The central part of the La-Ni-Si system has been investigated at 800 degrees C by means of single crystal X-ray diffraction, microscopy and analytical microprobe techniques. The result led to the identification of four new metal-rich silicides: LaNi2Si (R3m, a = 4.0263(3) angstrom, c = 15.066(2) angstrom, Z = 3), La2Ni3Si2 (P2(1)/c, a = 6.8789(7) angstrom, b = 6.2167(3) angstrom, c = 12.214(1) angstrom, beta = 90.92(1), Z = 4), La3Ni3Si2 (Pnma, a = 7.501(2) angstrom, b = 14.316(4) angstrom, c = 6.149(2) angstrom, Z = 4), La6Ni7Si4 (Pbcm, a = 6.066(1) angstrom, b = 7.488(1) angstrom, c = 29.682(5) angstrom, Z = 4). LaNi2Si belongs to the SrCu2Ga structure type, which is not represented among silicides, while La2Ni3Si2 crystallizes in its own structure type. Both compounds feature layered polyanionic motifs consisting of Ni and Si, which are separated by La. Instead, La6Ni7Si4 and La3Ni3Si2 are characterized by polyanionic networks. The former compound belongs to the Pr6Ni7Si4 structure type, with only two other representatives (Ce and Nd); the latter has been observed only with Rh and Ir. The two structures reveal close structural relationships having multiple identical slabs. Tight-binding electronic structure calculations by linear muffin-tin-orbital methods were performed for LaNi2Si, La2Ni3Si2 and La3Ni3Si2 to gain insights into their structure-bonding relationships. Their band structures suggest a metallic character for all compounds. The overall crystal orbital Hamilton populations are dominated by polar Ni-Si bonds, though homoatomic Ni-Ni and La-Ni(Si) bond contributions are not negligible. The variety of bonding patterns may serve as a logical explanation for the number of discovered compounds in this system as well as for the diversity of the observed structures.

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  • 16.
    Paul-Boncour, V
    et al.
    Univ Paris Est Creteil, ICMPE UMR7182, CNRS, 2 Rue Henri Dunant, F-94320 Thiais, France..
    Herrero, A.
    Univ Paris Est Creteil, ICMPE UMR7182, CNRS, 2 Rue Henri Dunant, F-94320 Thiais, France.;Univ Basque Country, UPV EHU, Dept Fis Aplicada 1, Escuela Ingn Bilbao, Plaza Torres Quevedo 1, Bilbao 48013, Spain..
    Shtender, Vitalii
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Univ Paris Est Creteil, ICMPE UMR7182, CNRS, 2 Rue Henri Dunant, F-94320 Thiais, France.
    Provost, K.
    Univ Paris Est Creteil, ICMPE UMR7182, CNRS, 2 Rue Henri Dunant, F-94320 Thiais, France..
    Elkaim, E.
    SOLEIL, LOrme Merisiers, BP 48, F-91192 Gif Sur Yvette, France..
    Magnetic transitions with magnetocaloric effects near room temperature related to structural transitions in Y0.9Pr0.1Fe2D3.5 deuteride2021In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 130, no 11, article id 113904Article in journal (Refereed)
    Abstract [en]

    The structural and magnetic properties of Y0.9Pr0.1Fe2D3.5 deuteride have been investigated by synchrotron and neutron diffraction, magnetic measurements, and differential scanning calorimetry. Deuterium insertion induces a 23.5% cell volume increase and a lowering of crystal symmetry compared to the cubic C15 Y0.9Pr0.1Fe2 parent compound (Fd-3m SG). The deuteride is monoclinic (P2(1)/c SG) below 330 K and undergoes a first-order transition between 330 and 350 K toward a pseudo-cubic structure (R-3 m SG) with TO-D = 342(2) K. In both structures, the D atoms are located in 96% R2Fe2 and 4% RFe3 tetrahedral interstitial sites (R = Y0.9Pr0.1). The compound is ferromagnetic, accompanied by a magnetostrictive effect below T-C = 274 K. The analysis of the critical exponents indicates a second-order type transition with a deviation from the isotropic 3D Heisenberg model toward the 3D XY model. This implies an easy plane of magnetization in agreement with cell parameter variation showing planar magnetic orientation. A weak magnetic peak is even observed at the order-disorder transition with a maximum at 343 K. Magnetic entropy variations are characteristic of direct and inverse magnetocaloric effects at T-C and TO-D, respectively.

  • 17.
    Paul-Boncour, Valerie
    et al.
    Univ Paris Est Creteil, CNRS, ICMPE, UMR 7182, F-94320 Thiais, France..
    Beran, Premysl
    Czech Acad Sci, Nucl Phys Inst, Rez 25068, Czech Republic.;European Spallat Source, ESS ERIC, SE-22100 Lund, Sweden..
    Hervoches, Charles
    Czech Acad Sci, Nucl Phys Inst, Rez 25068, Czech Republic..
    Shtender, Vitalii
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering. Univ Paris Est Creteil, CNRS, ICMPE, UMR 7182, F-94320 Thiais, France..
    TbMgNi4-xCox-(H,D)2 System. II: Correlation between Structural and Magnetic Properties2023In: ACS Omega, E-ISSN 2470-1343, Vol. 8, no 33, p. 30727-30735Article in journal (Refereed)
    Abstract [en]

    The magnetic properties of TbMgNi4-xCox intermetallic compounds and selected hydrides and deuterides of this system have been studied by various techniques, including magnetic measurements, in situ X-ray and neutron powder diffraction. The intermetallic compounds crystallize in a SnMgCu4-type structure and magnetically order below a Curie temperature (T-C), which increases exponentially with the Co content. This can be due to the ordering of the Co sublattice. On the other hand, the insertion of D or H in TbMgNiCo3 strongly decreases T-C. The X-ray diffraction measurements versus temperature reveal cell volume minima at T-C for the compounds with x = 1-3 without any hints of the structure change. The analysis of the neutron diffraction patterns for the intermetallics with x = 2 and 3 indicates a slightly canted ferrimagnetic structure below T-C. The Tb moments refined at 16 K are 4.1(2) (mu B)/Tb for x = 2, and 6.2(1) mu B/Tb for x = 3, which are smaller than the free ion value (9.5 mu B/Tb). This reduction can be due to the influence of temperature but also reveals the crystal field effect. As Ni and Co occupy statistically the same Wyckoff site, an average Ni/Co moment was refined, leading to 1.7(2) (mu B)/atom for x = 2 and 1.8(1) mu B/atom for x = 3 at 16 K. This moment is slightly canted compared to the Tb moment.

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  • 18.
    Shtender, Vitalii
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Hedlund, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Rosenqvist Larsen, Simon
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Structural and magnetic properties of new members of the 3:29 phase from the Ce-Fe-Mn system and 1:11 from the Ce-Co-Mn2021In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 855, article id 157435Article in journal (Refereed)
    Abstract [en]

    The Ce–Fe–Mn and Ce–Co–Mn systems have been re-visited with the intent of finding new potential phases for application as permanent magnets. Two new ternary compounds, Ce3(Fe0.638Mn0.362)29 (Nd3(Fe,Ti)29-type, space group P21/c, No. 14, Pearson Symbol mP128) and CeCo8Mn3 (Ce(Ni,Mn)11-type, space group P4/mbm, No. 127, Pearson Symbol tP24) have been discovered in the compositional range where the Ce2(T,Mn)17 (T = Fe, Co) phases are expected to exist with a (H)–Th2Ni17-type structure (space group P63/mmc, No. 194, Pearson Symbol hP38). Detailed investigations of the crystal structures have been performed using X-ray powder diffraction (XRPD) with supporting energy-dispersive X-ray (EDS) analysis. Compositions of the new compounds have been defined based on the EDS analysis as follows: Ce9.7Fe57.5Mn32.8 and Ce9.2Co65.2Mn25.6. A short discussion on the crystal structure peculiarities of the 1:5, 1:11, 1:12, 2:17 and 3:29 compounds in the Ce–T–Mn (T = Fe, Co, Ni, Cu) systems has been made. We present magnetic measurements on selected representatives of the studied phases. The most interesting being the Ce3(Fe0.638Mn0.362)29 phase which has a transition temperature well above room temperature. CeNi4.95Mn6.05 and CeCo8Mn3 exhibits properties characteristic of a canted antiferromagnetic state.

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  • 19.
    Shtender, Vitalii
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Univ Paris Est, ICMPE UMR7182, CNRS, UPEC, F-94320 Thiais, France.;NAS Ukraine, Karpenko Phys Mech Inst, 5 Naukova St, UA-79060 Lvov, Ukraine..
    Paul-Boncour, Valerie
    Univ Paris Est, ICMPE UMR7182, CNRS, UPEC, F-94320 Thiais, France..
    Denys, Roman
    HYSTORSYS AS, Box 45, NO-2027 Kjeller, Norway..
    Hedlund, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Zavaliy, Ihor
    NAS Ukraine, Karpenko Phys Mech Inst, 5 Naukova St, UA-79060 Lvov, Ukraine..
    Impact of the R and Mg on the structural, hydrogenation and magnetic properties of R3-xMgxCo9 (R = Pr, Nd, Tb and Y) compounds2022In: Materials research bulletin, ISSN 0025-5408, E-ISSN 1873-4227, Vol. 156, article id 111981Article in journal (Refereed)
    Abstract [en]

    R2MgCo9 (R = Pr, Nd, Tb and Y) compounds have been synthesized by a powder sintering method and the corresponding hydrides have been prepared by a solid gas method. Their crystal structures and magnetic properties have been systematically studied. X-ray diffraction analysis showed that all R2MgCo9 compounds belong to the PuNi3-type structure. The elements Tb, Y, Nd, Pr yield a lowering of the equilibrium pressure which correlates well with the increase in cell volume. The R2MgCo9H(D)x (R = Pr, Nd, Tb and Y; (9.4 <= x <= 12)) hydrides (deuterides) preserve the PuNi3-type structure with hydrogenation-induced volume expansion ranging from 14.7 to 19.6%. The substitution of deuterium for hydrogen in R2MgCo9-(H,D)(2) (R = Tb and Y) prevents fast desorption at room temperature and ambient pressure. As for the magnetic properties, all the studied interme-tallic compounds show ferromagnetic or ferrimagnetic behavior, and in some cases a temperature dependent spin reorientation. Hydrogen insertion reduces the magnetization and decreases the magnetic ordering temperature (TC), whereas Mg for R substitution increases TC.

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  • 20.
    Shtender, Vitalii
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Rosenqvist Larsen, Simon
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Variants of the X-phase in the Mn-Co-Ge system2021In: ACTA CRYSTALLOGRAPHICA SECTION C-STRUCTURAL CHEMISTRY, ISSN 2053-2296, Vol. 77, p. 176-180Article in journal (Refereed)
    Abstract [en]

    We report two new variants of the X-phase (orthorhombic, space group Pnnm) derived from the Mn-Co-Ge system. Two compositionally related crystals were investigated by means of single-crystal X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS). The Mn14.9Co15.5Ge6.6 and Mn14Co16.2Ge6.8 intermetallic compounds are part of the homogeneity region of the X-phase and adopt the Mn-14(Mn0.11Co0.64Si0.25)(23) structure type. The composition obtained from refinement of the XRD data is in agreement with the EDS results. In the present study, chemical disorder was only detected on the 8h positions. The ordering is compared with other members of the X-phase family and shows that the degree of disordering depends on the chemical composition. No completely ordered variants of the X-phase have yet been reported.

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  • 21.
    Shtender, Vitalii
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Smetana, Volodymyr
    Stockholm Univ, Dept Mat & Environm Chem, Svante Arrhenius Vag 16c, S-10691 Stockholm, Sweden.;Aarhus Univ, Dept Biol & Chem Engn, DK-8000 Aarhus C, Denmark.;Aarhus Univ, iNANO, DK-8000 Aarhus C, Denmark..
    Crivello, Jean -Claude
    Univ Paris Est Creteil, CNRS, ICMPE, UMR7182, 2 Rue Henri Dunant, F-94320 Thiais, France.;CNRS St Gobain NIMS, IRL 3629, Lab Innovat Key Mat & Struct LINK, Tsukuba, Ibaraki 3050044, Japan..
    Kravets, Anatolii
    Royal Inst Technol, Nanostruct Phys, S-10691 Stockholm, Sweden.;NAS Ukraine, Inst Magnetism, UA-03142 Kiev, Ukraine.;MES Ukraine, UA-03142 Kiev, Ukraine..
    Gondek, Lukasz
    AGH Univ Krakow, Fac Phys & Appl Comp Sci, Mickiewicza 30, PL-30059 Krakow, Poland..
    Mudring, Anja-Verena
    Stockholm Univ, Dept Mat & Environm Chem, Svante Arrhenius Vag 16c, S-10691 Stockholm, Sweden.;Aarhus Univ, Dept Biol & Chem Engn, DK-8000 Aarhus C, Denmark.;Aarhus Univ, iNANO, DK-8000 Aarhus C, Denmark..
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Intermetallics of 4:4:1 and 3:3:1 series in La-(Co,Ni)-M (M = Bi, Pb, Te, Sb, Sn and Ga, Al) systems and their properties2024In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 982, article id 173767Article in journal (Refereed)
    Abstract [en]

    Two series of isostructural intermetallics have been discovered in our search for new compounds with fused honeycomb motifs, both stable at elevated temperatures (1073 K). They crystallize with orthorhombic unit cells - La4Co4M (M = Sn, Sb, Te, Pb, Bi, SG Pbam, a = 8.247-8.315(2), b = 21.913-22.137(7), c = 4.750-4.664(2) angstrom, V = 850.5-869.5(4) angstrom 3, Z = 4) and La3Ni3M (M = Al, Ga, SG Cmcm, a = 4.1790-4.2395(1), b = 10.4921-10.6426 (6), c = 13.6399-13.7616(8) angstrom, V = 606.72-612.05(7), Z = 3). The crystal structures represent interesting variations of semiregular tilings of corrugated anionic layers and predominantly cationic zigzag motifs. The La4Co4M compounds reveal a complex type of ordering with a high degree of frustration as could be expected for the Kagome ' -related lattices, while magnetic ordering in the La3Ni3M series is less evident. Electronic structure calculations have been performed for multiple compounds within both series revealing metallic character and visible local minima around the Fermi level. The bonding picture is characterized by nearly equal contributions from the anionic and the cationic components.

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  • 22.
    Shtender, Vitalii
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Smetana, Volodymyr
    Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden..
    Crivello, Jean-Claude
    Univ Paris Est Creteil, CNRS, ICMPE, F-94320 Thiais, France..
    Gondek, Lukasz
    AGH Univ Sci & Technol, Fac Phys & Appl Comp Sci, PL-30059 Krakow, Poland..
    Przewozznik, Janusz
    AGH Univ Sci & Technol, Fac Phys & Appl Comp Sci, PL-30059 Krakow, Poland..
    Mudring, Anja-Verena
    Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden..
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Honeycomb Constructs in the La-Ni Intermetallics: Controlling Dimensionality via p-Element Substitution2023In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 62, no 37, p. 14843-14851Article in journal (Refereed)
    Abstract [en]

    The new ternary compounds La15Ni13Bi5 and La9Ni8Sn5 were obtained by arc melting under argon from appropriate amounts of the elements and subsequent annealing at 800 degrees C for 2 weeks. Single-crystal X-ray diffraction reveals that they represent two new structure types: La15Ni13Bi5 crystallizes in the hexagonal space group P62m [hP33, a = 14.995(3), c = 4.3421(10) Å, V = 845.5(4) Å3, Z = 1] and La9Ni8Sn5 in P63/m [hP88, a = 23.870(15), c = 4.433(3) Å, V = 2187(3) Å3, Z = 4]. The crystal structures of both compounds are characterized by hexagonal honeycomb-based motifs formed by Ni and Sn that extend along the c axis. The building motif with its three-blade wind turbine shape is reminiscent of the organic molecule triptycene and is unprecedented in extended solids. First-principles calculations have been performed in order to analyze the electronic structure and provide insight into chemical bonding. They reveal significant electron transfer from La to Ni and the respective p-element, which supports the formation of the polyanionic Ni-p-element network. DFT calculations suggest paramagnetic-like behavior for both compounds, which was confirmed by magnetic measurements.

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  • 23.
    Shtender, Vitalii
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Stopfel, Henry
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Hedlund, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Karlsson, Dennis
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Pothala, Rajasekhar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Skårman, Björn
    Hoganas AB, Bruksgatan 35, S-26383 Hoganas, Sweden..
    Olsson, Fredrik
    Hoganas AB, Bruksgatan 35, S-26383 Hoganas, Sweden..
    Vidarsson, Hilmar
    Höganäs AB, Bruksgatan 35, 263 83, Höganäs, Sweden..
    Andersson, Gabriella
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Influence of nano-VC on the structural and magnetic properties of MnAlC-alloy2021In: Scientific Reports, E-ISSN 2045-2322, Vol. 11, article id 14453Article in journal (Refereed)
    Abstract [en]

    Alloys of Mn55Al45C2 with additions of VC nano-particles have been synthesized and their properties evaluated. The Mn55Al45C2(VC)(x) (x=0.25, 0.5 and 1) alloys have been prepared by induction melting resulting in a high content of the ferromagnetic tau -phase (>94 wt.%). Powder X-ray diffraction indicates that nano-VC can be dissolved in the alloy matrix up to 1 at.%. On the other side, metallography investigations by scanning electron microscopy and scanning transmission electron microscope show inclusions of the nanosized additives in the microstructure. The effect of nano-VC on the grain and twin boundaries has been studied by electron backscattering diffraction. The magnetization has been measured by magnetometry up to 9 T while the domain structure has been studied using both magnetic force microscopy as well as Kerr-microscopy. For nano-VC contents above 0.25 at.%, a clear increase of the coercive force is observed, from 57 to 71 kA/m. The optimum appears to be for 0.5 at.% nano-VC which shows a 25% increase in coercive force without losing any saturation magnetization. This independent increase in coercivity is believed to originate from the nano-VC reducing the overall magnetic domain size. Overall, we observe that addition of nano-VC could be an interesting route to increase the coercive force of MnAl, without sacrificing saturation magnetization.

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  • 24.
    Vishina, Alena
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Hedlund, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Shtender, Vitalii
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Delczeg-Czirjak, Erna K.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Larsen, Simon R.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Vekilova, Olga Yu.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden.
    Huang, Shuo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Vitos, Levente
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol, Dept Mat Sci & Engn, Appl Mat Phys, SE-10044 Stockholm, Sweden.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Örebro Univ, Sch Sci & Technol, SE-70182 Örebro, Sweden.
    Herper, Heike C.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Data-driven design of a new class of rare-earth free permanent magnets2021In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 212, article id 116913Article in journal (Refereed)
    Abstract [en]

    A new class of rare-earth-free permanent magnets is proposed. The parent compound of this class is Co3Mn2Ge, and its discovery is the result of first principles theory combined with experimental synthesis and characterisation. The theory is based on a high-throughput/data-mining search among materials listed in the ICSD database. From ab-initio theory of the defect free material it is predicted that the saturation magnetization is 1.71 T, the uniaxial magnetocrystalline anisotropy is 1.44 MJ/m3, and the Curie temperature is 700 K. Co3Mn2Ge samples were then synthesized and characterised with respect to structure and magnetism. The crystal structure was found to be the MgZn2-type, with partial disorder of Co and Ge on the crystallographic lattice sites. From magnetization measurements a saturation polarization of 0.86 T at 10 K was detected, together with a uniaxial magnetocrystalline anisotropy constant of 1.18 MJ/m3, and the Curie temperature of TC = 359 K. These magnetic properties make Co3Mn2Ge a very promising material as a rare-earth free permanent magnet, and since we can demonstrate that magnetism depends critically on the amount of disorder of the Co and Ge atoms, a further improvement of the magnetism is possible. We demonstrate here that the class of compounds based on T3Mn2X (T = Co or alloys between Fe and Ni; X = Ge, Al or Ga) in the MgZn2 structure type, form a new class of rare-earth free permanent magnets with very promising performance.

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