Polarized IR and Raman spectra of Ca₂MgSi₂O₇, Ca₂ZnSi₂O₇ and Sr₂MgSi₂O₇ single crystals: Temperature-dependent studies of commensurate to incommensurate and

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• 作者：J. Hanuza^a ; ^b ; M. Ptak^a ; ^{m.ptak@int.pan.wroc.pl} ; M. M膮czka^a ; K. Hermanowicz^a ; J. Lorenc^b ; A.A. Kaminskii^c
• 关键词：Ca2ZnSi2O7 ; Polarized IR and Raman spectra ; Phonon calculation ; LO&ndash ; TO splitting ; Phase transition ; Stimulated Raman effect
• 刊名：Journal of Solid State Chemistry
• 出版年：2012
• 期刊代码：130_00224596
• 类别：ch
• 出版时间：July, 2012
• 卷：191
• 期：Complete
• 页码：90-101
• 文件大小：1905 K

摘要

IR and Raman spectra of Ca₂MgSi₂O₇, Ca₂ZnSi₂O₇ and Sr₂MgSi₂O₇ oriented single crystals and powders have been measured. The temperature dependence of phonons has been established in the 4-650 K range. Discussion of the results has been performed on the basis of factor group approach for the tetragonal P4虅2₁m (D_2d³) space group with Z=2. The assignment of the bands observed to the internal and external modes has been made on their polarization behaviour, phonon energy calculations and literature data. The evidences of the LO-TO splitting and commensurate (C) to incommensurate (IC) as well as incommensurate (IC) to normal (N) phase transitions have been found. As a representative example, the results obtained for the spontaneous Raman scattering have also been used in the discussion of the stimulated Raman spectra of Ca₂ZnSi₂O₇.