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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: 2019-08-12Bibliographically 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: 2019-06-10Bibliographically 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: 2019-05-24Bibliographically 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
El Hachmi, A., Tamraoui, Y., Manoun, B., Haloui, R., Elaamrani, M. A., Saadoune, I., . . . Lazor, P. (2018). Synthesis and Rietveld refinements of new ceramics Sr2CaFe2WO9 and Sr2PbFe2TeO9 perovskites. Powder Diffraction, 33(2), 134-140
Open this publication in new window or tab >>Synthesis and Rietveld refinements of new ceramics Sr2CaFe2WO9 and Sr2PbFe2TeO9 perovskites
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2018 (English)In: Powder Diffraction, ISSN 0885-7156, E-ISSN 1945-7413, Vol. 33, no 2, p. 134-140Article in journal (Refereed) Published
Abstract [en]

Ceramics of Sr2CaFe2WO9 and Sr2PbFe2TeO9 double perovskites have been prepared in polycrystalline form by solid-state technique, in the air. The crystalline structure was analyzed using X-ray powder diffraction (XRPD) at room temperature. Rietveld analysis of XRPD) patterns show that both compounds adopt a tetragonal structure with space group I4/m, with unit cell parameters a = 5.5453(1) angstrom, c = 7.8389(1) angstrom for Sr(2)CaFc(2)WO(9), and a = 5.5994(15) angstrom, c = 7.8979(30) angstrom for Sr2PbFe2TeO9. A certain degree of anti-site disordering of W and/or Te and Fe on the B -sites have been detected, indicating the presence of a partial amount of W and/or Te at Fe positions and vice versa.

Place, publisher, year, edition, pages
J C P D S-INT CENTRE DIFFRACTION DATA, 2018
Keywords
Sr2CaFe2WO9, Sr2PbFe2TeO9 crystal structure, X-ray diffraction
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-360482 (URN)10.1017/S0885715618000222 (DOI)000437156500008 ()
Funder
Swedish Research Council, 348- 2014-4287
Available from: 2018-09-17 Created: 2018-09-17 Last updated: 2018-09-17Bibliographically approved
Manoun, B., Tamraoui, Y., Saadoune, I., Lazor, P., Yang, W. & Alami, J. (2017). Crystal structure and high temperature Raman spectroscopy of Sr2ZnTeO6 double perovskite. MATERIALS RESEARCH EXPRESS, 4(10), Article ID 105018.
Open this publication in new window or tab >>Crystal structure and high temperature Raman spectroscopy of Sr2ZnTeO6 double perovskite
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2017 (English)In: MATERIALS RESEARCH EXPRESS, ISSN 2053-1591, Vol. 4, no 10, article id 105018Article in journal (Refereed) Published
Abstract [en]

Sr2ZnTeO6 double-perovskite oxide has been synthesized using solid state chemistry. As synthesized, the crystalline structure of Sr2ZnTeO6, refined using x-ray diffraction, is monoclinic having the space group I2/m. Structural phase transitions are studied using Raman spectroscopy in the temperature range 25 degrees C-567 degrees C. It is found that two of three observed bending Raman vibrations merge together at a temperature of around 120 degrees C, indicating a Sr2ZnTeO6 phase transition from the monoclinic (I2/m) to the tetragonal (I4/m). Furthermore, a temperature-dependence change-rate of external and O-Te-O bending modes and stretching modes are detected at 270 degrees C, which is interpreted as a phase transition from the tetragonal (I4/m) to the cubic (Fm-3m) structure.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2017
Keywords
double perovskite, phase transition, Raman spectroscopy, Sr2ZnTeO6
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-342607 (URN)10.1088/2053-1591/aa8d87 (DOI)000415251700004 ()
Funder
Swedish Research Council, 348-2014-4287
Available from: 2018-02-23 Created: 2018-02-23 Last updated: 2018-02-23Bibliographically approved
Es-Soufi, H., Bih, L., Manoun, B. & Lazor, P. (2017). Structure, thermal analysis and optical properties of lithium tungsten-titanophosphate glasses. Journal of Non-Crystalline Solids, 463, 12-18
Open this publication in new window or tab >>Structure, thermal analysis and optical properties of lithium tungsten-titanophosphate glasses
2017 (English)In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 463, p. 12-18Article in journal (Refereed) Published
Abstract [en]

A melt-quenching method is used to prepare homogeneous glasses inside the 20Li(2)O-(50-x)Li2WO4-xTiO(2)-30P(2)O(5) (x = 0, 5, 8,10 and 15 mol%) system. The amorphous and glassy states of the glasses are evidenced by the X-ray diffraction and differential scanning calorimetry (DSC) analysis, respectively. The glasses were found to be colorless. The determined parameters for the glasses such as density, molar volume and glass transition temperature (T-g) depend strongly on the chemical composition of the glasses. The density and T-g are found to decrease and increase with TiO2 content, respectively. Infrared (IR) spectroscopy is used to characterize their structural approach. This technique has allowed the identification of different phosphate structural units mainly pyrophosphate and metaphosphate in their structure. From the absorption edge studies, the values of the optical band gap, E-g, and Lirbach energy, Delta E, were evaluated. The optical band gap is found to depend on the glass composition and it decreases as the content of the TiO2 increases. (C) 2017 Elsevier B.V. All rights reserved.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
Phosphate, Glasses, DSC, IR spectroscopy, Optical properties
National Category
Geochemistry
Identifiers
urn:nbn:se:uu:diva-330050 (URN)10.1016/j.jnoncrysol.2017.02.013 (DOI)000405154700003 ()
Available from: 2017-11-09 Created: 2017-11-09 Last updated: 2017-11-09Bibliographically approved
El Aamrani, A., Manoun, B., Abkar, R., Tamraoui, Y., Mirinioui, F.-e., El Hachmi, A., . . . Lazor, P. (2017). Synthesis, crystal Structure and temperature induced phase transition in Ba1/5Sr4/5NiMoO6 double perovskite oxide:: Study by X-ray diffraction and Raman spectroscopy. Journal of Applied Surfaces and Interfaces, 2(1-3), 27-33
Open this publication in new window or tab >>Synthesis, crystal Structure and temperature induced phase transition in Ba1/5Sr4/5NiMoO6 double perovskite oxide:: Study by X-ray diffraction and Raman spectroscopy
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2017 (English)In: Journal of Applied Surfaces and Interfaces, Vol. 2, no 1-3, p. 27-33Article in journal (Refereed) Published
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-372583 (URN)
Available from: 2019-01-07 Created: 2019-01-07 Last updated: 2019-07-18
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-9992-8009

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