Dataset Information

Lattice Dynamics and Structural Phase Transitions in Eu₂O₃.

ABSTRACT: Using the density functional theory, we study the structural and lattice dynamical properties of europium sesquioxide (Eu₂O₃) in the cubic, trigonal, and monoclinic phases. The obtained lattice parameters and energies of the Raman modes show a good agreement with the available experimental data. The Eu-partial phonon density of states calculated for the cubic structure is compared with the nuclear inelastic scattering data obtained from a 20 nm thick Eu₂O₃ film deposited on a YSZ substrate. A small shift of the experimental spectrum to higher energies results from a compressive strain induced by the substrate. On the basis of lattice and phonon properties, we analyze the mechanisms of structural transitions between different phases of Eu₂O₃.

SUBMITTER: Lazewski J

PROVIDER: S-EPMC8277167 | biostudies-literature | 2021 Jul

REPOSITORIES: biostudies-literature

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Lattice Dynamics and Structural Phase Transitions in Eu2O3.

Łażewski Jan J Sternik Małgorzata M Jochym Paweł T PT Kalt Jochen J Stankov Svetoslav S Chumakov Aleksandr I AI Göttlicher Jorg J Rüffer Rudolf R Baumbach Tilo T Piekarz Przemysław P

Inorganic chemistry 20210618 13

Using the density functional theory, we study the structural and lattice dynamical properties of europium sesquioxide (Eu2O3) in the cubic, trigonal, and monoclinic phases. The obtained lattice parameters and energies of the Raman modes show a good agreement with the available experimental data. The Eu-partial phonon density of states calculated for the cubic structure is compared with the nuclear inelastic scattering data obtained from a 20 nm thick Eu2O3</ ...[more]

PMID: 34143607

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Project description:The intriguing functional nature of ceramics containing rare earth sesquioxide (RES) is associated with the type of polymorphic structure they crystallize into. They prefer to be in the cubic, monoclinic or hexagonal structure in the increasing order of cation size, RRE. Since the functional properties of these ceramics varies with RRE, temperature and pressure, a systematic investigation delineating the cation size effect is indispensable. In the present work we report the structural stability and compressibility behaviour of the RES ceramics, (Eu1-xLax)2O3, of RESs with dissimilar structure and significant difference in cationic radii. The selected compositions of (Eu1-xLax)2O3 have been studied using the in-situ high pressure synchrotron X-ray diffraction and the structural parameters obtained through Rietveld refinement. The cubic structure, which is stable for 0.95 Å [Formula: see text] RRE [Formula: see text] Å at ambient temperature and pressure (ATP), prefers a cubic to hexagonal transition at high pressures. The biphasic region of cubic and monoclinic structure, which is stable for 0.98 Å [Formula: see text] RRE [Formula: see text] Å at ATP, prefers a cubic/monoclinic to hexagonal transition at high pressures. Further, in the biphasic region of monoclinic and hexagonal structure, observed for 1.025 Å [Formula: see text]RRE [Formula: see text] Å, the monoclinic phase is found to be progressing towards the hexagonal phase with increasing pressure. The pure hexagonal phase obtained for 1.055 Å [Formula: see text] RRE [Formula: see text] 1.10 Å is found to be structurally stable at high pressures. The bulk moduli are obtained from the Birch-Murnaghan equation of state fit to the compressibility data and its dependance on the cation size is discussed. The microstrain induced by the difference in cation size causes an internal pressure in the crystal structure leading to a reduction in the bulk modulus of [Formula: see text] and 0.6. A pressure-concentration (P-x) phase diagram upto a pressure of 25 GPa is constructed for (Eu1-xLax)2O3. This would provide an insight to the fundamental and technological aspects of these materials and the RESs in general.

Dataset Information

Lattice Dynamics and Structural Phase Transitions in Eu₂O₃.

Publications

Lattice Dynamics and Structural Phase Transitions in Eu<sub>2</sub>O<sub>3</sub>.

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