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Publications (10 of 108) Show all publications
Jerroudi, M., Bih, L., Azrour, M., Manoun, B., Saadoune, I. & Lazor, P. (2020). Investigation of Novel Low Melting Phosphate Glasses Inside the Na2O-K2O-ZnO-P2O5 System. JOURNAL OF INORGANIC AND ORGANOMETALLIC POLYMERS AND MATERIALS, 30(2), 532-542
Open this publication in new window or tab >>Investigation of Novel Low Melting Phosphate Glasses Inside the Na2O-K2O-ZnO-P2O5 System
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2020 (English)In: JOURNAL OF INORGANIC AND ORGANOMETALLIC POLYMERS AND MATERIALS, ISSN 1574-1443, Vol. 30, no 2, p. 532-542Article in journal (Refereed) Published
Abstract [en]

Phosphate glasses containing different concentrations of zinc oxide inside the (1 - x)(NaPO3-KPO3)-xZnO system (0 <= x <= 50 mol%) have been prepared using the conventional melt quenching technique. The prepared glasses were transparent, bubble-free and colourless. Their density, molar volume, glass transition temperature, and structural properties using infrared and Raman spectroscopies are investigated. As the content of ZnO increases, the density increases while the molar volume decreases. The composition dependence of T-g shows a minimum for the glass (x = 20 mol%). Structural approach realized by IR and Raman spectroscopies reveals that zinc ions occupy different sites in the glassy-network, mainly modifier sites and middle phosphate network in low-zinc and high-zinc glasses, respectively. The introduction of ZnO in the network induces some structural rearrangements through the conversion of metaphosphate structural units to pyrophosphate ones. It is also highlighted that the presence of ZnO in the glassy matrix allows the transformation of some P-O-P and P=O bonds to P-O-Zn linkages. From the UV-Visible absorption studies, the values of the optical band gap, E-g, and Urbach energy, Delta E, were evaluated. The optical band gap is found to depend on the glasses composition. E-g and Delta E show a minimum and a maximum respectively, for the glass (x = 20 mol%).

Place, publisher, year, edition, pages
SPRINGER, 2020
Keywords
Phosphate, Glasses, Glass transition temperature, Structure, Optical properties
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-408206 (URN)10.1007/s10904-019-01213-0 (DOI)000519151600027 ()
Available from: 2020-04-06 Created: 2020-04-06 Last updated: 2020-04-06Bibliographically approved
Liu, L., Skogby, H., Ivanov, S., Weil, M., Mathieu, R. & Lazor, P. (2019). Bandgap engineering in Mn3TeO6: giant irreversible bandgap reduction triggered by pressure. Chemical Communications, 55(80), 12000-12003
Open this publication in new window or tab >>Bandgap engineering in Mn3TeO6: giant irreversible bandgap reduction triggered by pressure
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2019 (English)In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 55, no 80, p. 12000-12003Article in journal (Refereed) Published
Abstract [en]

In this study, the bandgap energy of the multiferroic oxide Mn3TeO6 is successfully reduced by similar to 39% from 3.15 eV to 1.86 eV, accompanied by a phase transition at high pressures. The high-pressure phase with smaller bandgap energy is quenchable to ambient conditions and represents a promising light-harvesting material for photovoltaic applications.

National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-397942 (URN)10.1039/c9cc04821a (DOI)000496529500030 ()31524904 (PubMedID)
Funder
Swedish Research Council
Available from: 2020-01-02 Created: 2020-01-02 Last updated: 2020-01-02Bibliographically approved
Liu, L., Skogby, H., Ivanov, S., Weil, M., Mathieu, R. & Lazor, P. (2019). Bandgap engineering in Mn3TeO6: giant irreversible bandgap reduction triggered by pressure. Chemical Communications, 55, 12000
Open this publication in new window or tab >>Bandgap engineering in Mn3TeO6: giant irreversible bandgap reduction triggered by pressure
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2019 (English)In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 55, p. 12000-Article in journal (Refereed) Published
Abstract [en]

In this study, the bandgap energy of the multiferroic oxide Mn3TeO6 is successfully reduced by ∼39% from 3.15 eV to 1.86 eV, accompanied by a phase transition at high pressures. The high-pressure phase with smaller bandgap energy is quenchable to ambient conditions and represents a promising light-harvesting material for photovoltaic applications.

National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-395737 (URN)10.1039/C9CC04821A (DOI)
Available from: 2019-10-23 Created: 2019-10-23 Last updated: 2020-02-07Bibliographically approved
Liu, L., Lazor, P. & Li, X. (2019). Lattice distortion-induced sluggish phasetransition in CoCrFeNixAl1-x (x = 0.5, 0.75) highentropyalloys at high pressures. High Pressure Research, 39(4)
Open this publication in new window or tab >>Lattice distortion-induced sluggish phasetransition in CoCrFeNixAl1-x (x = 0.5, 0.75) highentropyalloys at high pressures
2019 (English)In: High Pressure Research, ISSN 0895-7959, E-ISSN 1477-2299, Vol. 39, no 4Article in journal (Refereed) Published
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:uu:diva-395736 (URN)10.1080/08957959.2019.1653865 (DOI)
Available from: 2019-10-23 Created: 2019-10-23 Last updated: 2020-02-18Bibliographically approved
Liu, L., Ivanov, S., Mathieu, R., Weil, M., Li, X. & Lazor, P. (2019). Pressure tuning of octahedral tilt in the ordered double perovskite Pb2CoTeO6. Journal of Alloys and Compounds, 801, 310-317
Open this publication in new window or tab >>Pressure tuning of octahedral tilt in the ordered double perovskite Pb2CoTeO6
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2019 (English)In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 801, p. 310-317Article in journal (Refereed) Published
Abstract [en]

Double perovskites represent a family of materials with promising fundamental properties (e.g. multiferroicity) and vast potential applications. However, the knowledge of pressure effects on the crystal structure of double perovskite is limited, which hinders their efficient synthesis using high-pressure techniques. Pb2CoTeO6 (PCTO) is considered as a good candidate for multiferroic materials, although a polymorph with a polar structure has not been synthesized yet. In the present study, the pressure effect on the crystal structure of PCTO was systematically studied by employing in situ synchrotron X-ray powder diffraction and Raman scattering techniques up to 60 GPa. A structural phase transition from R-3 to I2/m structure was observed at around 20 GPa, indicating that increasing the pressure has a similar effect on PCTO as decreasing the temperature, i.e., promoting the distortion of the structure. No polar structure of PCTO has been observed in the applied pressure range. The present study provides a valuable information about the crystal structure evolution of double perovskites upon compression, and will benefit high-pressure syntheses of novel double perovskites in the future. 

Place, publisher, year, edition, pages
ELSEVIER SCIENCE SA, 2019
Keywords
Double perovskite, Phase transition, High pressure, Raman spectroscopy, X-ray powder diffraction
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-390373 (URN)10.1016/j.jallcom.2019.06.096 (DOI)000474352000039 ()
Funder
Swedish Research Council
Available from: 2019-08-12 Created: 2019-08-12 Last updated: 2019-11-25Bibliographically approved
Liu, L., Huang, S., Vitos, L., Dong, M., Bykova, E., Zhang, D., . . . Lazor, P. (2019). Pressure-induced magnetovolume effect in CoCrFeAl high-entropy alloy. Communications Physics, 2, Article ID 42.
Open this publication in new window or tab >>Pressure-induced magnetovolume effect in CoCrFeAl high-entropy alloy
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2019 (English)In: Communications Physics, E-ISSN 2399-3650, Vol. 2, article id 42Article in journal (Refereed) Published
Abstract [en]

High-entropy alloys (HEAs) composed of multiple-principal elements with (nearly) equimolar ratio establish a new conceptual framework for alloy design and hold a promise for extensive applications in industry, akin to the controlled expansion alloys (CEAs), such as Invar alloys. Spontaneously, one question emerges - would it be possible to synthesize a novel class of alloys combining the virtues of both CEAs and HEAs? Here, we report the pressure-induced magnetovolume effect in the body-centered-cubic CoCrFeAl HEA coupled with magnetic phase transitions from ferromagnetic to paramagnetic, and to non-magnetic states, originating from the successive collapses of local magnetic moments of Co and Fe. The observed magnetovolume anomalies, occurring in a progressive way, tailor appreciably the coefficient of thermal expansion of CoCrFeAl. These results further strengthen HEAs’ anticipated potential for designing multifunctional materials in virtue of their multiple outstanding properties, and reveal possible routes for their future synthesis.

National Category
Condensed Matter Physics Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:uu:diva-382796 (URN)10.1038/s42005-019-0141-9 (DOI)000467220700001 ()
Available from: 2019-05-03 Created: 2019-05-03 Last updated: 2019-11-25Bibliographically approved
Liu, L., Song, H. X., Li, X., Zhang, D., Mathieu, R., Ivanov, S., . . . Lazor, P. (2019). Pressure-induced polymorphism and piezochromism in Mn2FeSbO6. Applied Physics Letters, 114(16), Article ID 162903.
Open this publication in new window or tab >>Pressure-induced polymorphism and piezochromism in Mn2FeSbO6
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2019 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 114, no 16, article id 162903Article in journal (Refereed) Published
Abstract [en]

In the last decade, major efforts have been devoted to searching for polar magnets due to their vast potential applications in spintronic devices. However, the polar magnets are rare because of conflicting electronic configuration requirements of ferromagnetism and electric polarization. Double-perovskite oxides with a polar structure containing transition metal elements represent excellent candidates for the polar magnet design. Herein, the crystal structure evolution of Mn2FeSbO6 (MFSO) was investigated at pressures reaching similar to 50 GPa by in situ synchrotron X-ray diffraction (XRD), Raman scattering, and ab initio calculation techniques. The XRD results reveal ilmenite-to perovskite-type phase transition at around 35 GPa. An additional intermediate phase, observed in the range of 31-36 GPa by Raman spectroscopy, but not the XRD technique, is proposed to represent the polar LiNbO3 phase. It is argued that this phase emerged due to the heating effect of the Raman-excitation laser. The LiNbO3-type MFSO compounds, displaying an intrinsic dipole ordering, represent a promising candidate for multiferroic materials. The detected phase transitions were found to be reversible although a significant hysteresis was noticeable between compression and decompression runs. Moreover, a pressure-induced piezochromism, signifying a bandgap change, was discovered by the direct visual observations and corroborated by ab initio calculations. The present study benefits an efficient high-pressure synthesis of polar magnetic double-perovskite oxides in the future.

Place, publisher, year, edition, pages
AMER INST PHYSICS, 2019
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-383857 (URN)10.1063/1.5090649 (DOI)000466264600024 ()
Available from: 2019-05-24 Created: 2019-05-24 Last updated: 2019-11-25Bibliographically approved
Li, N., Manoun, B., Tamraoui, Y., Zhang, Q., Dong, H., Xiao, Y., . . . Yang, W. (2019). Structural and electronic phase transitions of Co2Te3O8 spiroffite under high pressure. Physical Review B, 99(24), Article ID 245125.
Open this publication in new window or tab >>Structural and electronic phase transitions of Co2Te3O8 spiroffite under high pressure
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2019 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 99, no 24, article id 245125Article in journal (Refereed) Published
Abstract [en]

The structural and electronic phase transitions of Co2Te3O8 spiroffite have been studied with a suite of in situ high-pressure characterization techniques including synchrotron x-ray diffraction, Raman, x-ray emission spectroscopy, UV-vis absorption, and electrical transport measurement. Two pressure-induced phase transitions were observed at about 6.9 and 14.4 GPa. The first transition is attributed to a small spin transition of Co along with discontinuity in unit-cell volume change, while the second one represents a first-order phase transition with a volume collapse of 4.5%. The latter transition is accompanied by the relaxation of distortion in CoO6 octahedron, which enhances the crystal-field strength inhibiting the occurrence of spin transition. What is more, the competition between contributions of electrons and oxygen ion to the overall conductivity is observed and affected by the phase transition under high pressure. This demonstration provides insights into the relationship between the lattice-structural and spin degrees of freedom, and highlights the impact of pressure on the control of structural and electronic states of a given material for optimized functionalities.

Place, publisher, year, edition, pages
AMER PHYSICAL SOC, 2019
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-390212 (URN)10.1103/PhysRevB.99.245125 (DOI)000471983800003 ()
Available from: 2019-08-09 Created: 2019-08-09 Last updated: 2019-08-09Bibliographically approved
Weis, F., Lazor, P. & Skogby, H. (2018). Hydrogen analysis in nominally anhydrous minerals by transmission Raman spectroscopy. Physics and chemistry of minerals, 45(7), 597-607
Open this publication in new window or tab >>Hydrogen analysis in nominally anhydrous minerals by transmission Raman spectroscopy
2018 (English)In: Physics and chemistry of minerals, ISSN 0342-1791, E-ISSN 1432-2021, Vol. 45, no 7, p. 597-607Article in journal (Refereed) Published
Abstract [en]

We present a new approach for the analysis of water in nominally anhydrous minerals using transmission Raman spectroscopy. Using this approach, the laser was shone through thin, nearly transparent samples of clinopyroxene, garnet and synthetic rhyolite glass. To remove mineral-induced background and to improve the quality of the OH spectral region, specifically for clinopyroxene, a reference spectrum of a dehydrated crystal was measured and subtracted. Water contents of all clinopyroxene samples were previously determined by Fourier transformed infrared spectroscopy (FTIR). The application of transmission Raman spectroscopy and a reference spectrum of a dry sample revealed a noticeable improvement in the quality of spectra and thus the detection limit, compared to the standard backscattering configurations. We show that the quality of transmission spectra and the detection limit depend on the sample thickness, and that the thickness has to be taken into account when measuring and comparing OH-integrated intensity and water content if the results are used for OH quantification.

National Category
Geosciences, Multidisciplinary
Identifiers
urn:nbn:se:uu:diva-306207 (URN)10.1007/s00269-018-0945-2 (DOI)000436406600001 ()
Funder
Swedish Research Council
Available from: 2016-10-26 Created: 2016-10-26 Last updated: 2018-09-06Bibliographically approved
Es-soufi, H., Bih, H., Bih, L., Azrour, M., Manoun, B. & Lazor, P. (2018). Structure and some physical properties of sodium ion conducting glasses inside the Na2O‐Na2WO4‐TiO2‐P2O5 system. Journal of Applied Surfaces and Interfaces, 4(1-3), 1-8
Open this publication in new window or tab >>Structure and some physical properties of sodium ion conducting glasses inside the Na2O‐Na2WO4‐TiO2‐P2O5 system
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2018 (English)In: Journal of Applied Surfaces and Interfaces, Vol. 4, no 1-3, p. 1-8Article in journal (Refereed) Published
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-372570 (URN)
Available from: 2019-01-07 Created: 2019-01-07 Last updated: 2019-05-29Bibliographically approved
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