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Pressure, Temperature and Concentration Dependences of Phonon Frequency with Variable Grüneisen Parameter: Fits to the Raman‐Active E g Mode in TiO 2 and Ti 1—x Zr x O 2 (x ≤ 0.1)
Author(s) -
Hirata T.
Publication year - 1998
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/(sici)1521-3951(199809)209:1<17::aid-pssb17>3.0.co;2-r
Subject(s) - tetragonal crystal system , raman spectroscopy , materials science , phonon , orthorhombic crystal system , grüneisen parameter , condensed matter physics , analytical chemistry (journal) , thermodynamics , diffraction , chemistry , physics , crystallography , thermal expansion , optics , crystal structure , chromatography , metallurgy
Beginning with the mode Grüneisen parameter, the pressure, temperature and concentration dependences of phonon frequency have been derived under the condition of variable Grüneisen parameter with pressure, temperature and composition. Fits to the Raman‐active E g mode at ≈450 cm —1 in TiO 2 and Ti 1— x Zr x O 2 ( x ≤ 0.1) are presented, indicating that the experimental data are somewhat reproduced provided that the mode Grüneisen parameter in TiO 2 is a variable quantity. Besides, the concentration dependence of phonon frequency with variable Grüneisen parameter is applied to the Raman band at ≈500 cm —1 in YBa 2 Cu 3 O x , which is assigned to the A g symmetric stretching mode of the bridging oxygen and changes in frequency with x ; it is highlighted that the condition of variable Grüneisen parameter is significant to reproduce the frequency data, which indicate the tetragonal‐to‐orthorhombic transition at x ≈ 6.5 and change nonlinearly with x , whereas the x dependence of the unit‐cell volume is almost linear in conformity with Vegard's law.