Raman Scattering Study of Cubic to Tetragonal Phase Transitions in Mixed System A_xBa_<1-x>TiO_3

概要

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The ferroelectric phase transition with the point group change from m3m to 4mm in the mixed system A_xBa_<1-x>TiO_3 (A-Pb, Sr) was studied by Raman scattering measurements. The low frequency spectra show strong dependence on both composition and temperature. The square of the soft mode frequency shows a linear dependence on T_c. While, in temperature dependence, the soft mode of Pb_<0.14>Ba_<0.86>TiO_3 slightly decreases towards T_c on heating, but the softening is suppressed near T_c. Peak frequencies higher than 100 cm_<-1> are insensitive to both composition and temperature. The mode intensity gradually decreases with increasing temperature. In spite of the fact that all optical modes should be Raman inactive above T_c, a few modes are still observed in the spectra.
社団法人応用物理学会の論文
1996-09-30