High pressure raman study of the phase transition in pb(ti. 81,sn. 19)O3 and (pb. 22,Ba. 78)tiO3

We have measured the pressure dependent Raman scattering, at room temperature, of the k=0 phonon frequencies of Pb(Ti 81 Sn. 19)O3 and (Pb 22,Ba. 78)TiO3. Particular emphasis was placed on the soft modes, their damping, and their behavior near the phase transition to the cubic phase. We also discuss the determination of the transition pressure p as -well as the order of the phase transition. © 1984, Taylor & Francis Group, LLC. All rights reserved.