A RAMAN INVESTIGATION OF THE ORDERED COMPLEX PEROVSKITE PBMG0.5W0.5O3

The complex perovskite PbM(0.5)W(0.5)O(3), exhibiting a long-range B-s ite cation ordering, has been investigated by Raman scattering from 10 K up to 956 K. The Raman results are systematically treated, and anal ysed through the characteristic parameters of phonon peaks. The existe nce of an additional intermediate phase I between the low-temperature antiferroelectric phase A and the high-temperature paraelectric phase P has been demonstrated (T-AI similar or equal to 240 K, T-IP = 312 K) . These results were compared with dielectric measurements. The disapp earance of the first-order Raman structures near 1000 K in the paraele ctric phase is discussed in terms of dynamic disorder in the Ph and O sublattices.