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Structural stability of Sc 3 CrO 6 : A Raman spectroscopic study
Author(s) -
Kesari Swayam,
Todorov N.D.,
Marinova V.,
Rao Rekha
Publication year - 2020
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.5926
Subject(s) - raman spectroscopy , anharmonicity , phonon , thermal expansion , bulk modulus , raman scattering , monoclinic crystal system , chemistry , phase transition , molecular vibration , analytical chemistry (journal) , grüneisen parameter , atmospheric temperature range , soft modes , phase (matter) , materials science , crystal structure , condensed matter physics , crystallography , thermodynamics , optics , physics , optoelectronics , organic chemistry , chromatography , ferroelectricity , metallurgy , composite material , dielectric
Structural stability of the mixed rare earth‐transition metal oxide Sc 3 CrO 6 (space group R 3 ¯ ) is investigated at high pressures using Raman spectroscopy up to 23.8 GPa, at ambient temperature. Results indicate that the compound transforms reversibly to a lower symmetry phase above 18 GPa. Lattice dynamical calculations carried out using a shell model were used to obtain the bulk modulus and to estimate mode Grüneisen parameters from Raman spectroscopic data. From the nature of changes in the vibrational spectra and from the trends in iso‐structural compounds, we speculate the high pressure phase to be a monoclinic phase. On the other hand, temperature dependent Raman scattering studies in the temperature range 77–1,273 K, indicate disappearance of a few vibrational modes indicating increase in symmetry. From the pressure and temperature dependence of the Raman modes, using calculated bulk modulus and thermal expansion coefficient, anharmonicity of the modes is estimated. It is found that anharmonicity due to phonon–phonon decay is more dominant and the contribution of thermal expansion is small for all of the Raman modes.