Vibrational modes and overlap matrix of LiNb.sub.1-x./sub.Ta.sub.x./sub.O.sub.3./sub. mixed crystals

0504703 - FZÚ 2020 RIV US eng J - Journal Article
Bartasyte, A. - Margueron, S. - Glazer, A.M. - Simon, E. - Gregora, Ivan - Huband, S. - Thomas, P.A.
Vibrational modes and overlap matrix of LiNb_1-xTa_xO₃ mixed crystals.
Physical Review B. Roč. 99, č. 9 (2019), s. 1-13, č. článku 094306. ISSN 2469-9950. E-ISSN 2469-9969
Institutional support: RVO:68378271
Keywords : mixed crystals * IR and Raman spectroscopy * lattice vibrations
OECD category: Condensed matter physics (including formerly solid state physics, supercond.)
Impact factor: 3.575, year: 2019
Method of publishing: Limited access
https://doi.org/10.1103/physrevb.99.094306

The wave numbers and strengths of the lattice vibrational modes of LiNbO3-LiTaO3 solid solutions have been studied by Raman and IR spectroscopy. The substitution of Nb by Ta induces shifts of wave numbers and intensities of phonon modes indicating a one-phonon behavior. The wave numbers of low-frequency vibrations soften with the increased atomic mass. The frequencies of most of the high-frequency modes increase with the Ta/Nb ratio. A qualitative relation between the shift of transverse and longitudinal modes in the solid solutions has been found on the basis of an overlap matrix. The exceptional softening of several high-frequency modes with the replacement of Nb by Ta originates from strong interaction of these modes with modes at low frequencies according to the overlap matrix. The intensities of the Raman modes are strongly modulated by the electronic properties with Ta/Nb substitution and this explains their role in the physical properties of LiNbO3 and LiTaO3.
Permanent Link: http://hdl.handle.net/11104/0296283