Direct evidence of soft mode behavior near the Burns temperature in the PbMg1/3Nb2/3O3 relaxor ferroelectric -: art. no. 214101

Inelastic neutron scattering measurements of the relaxor ferroelectric PbMg1/3Nb2/3O3 (PMN) in the temperature range 490 K<880 K directly observe the soft mode (SM) associated with the Curie-Weiss behavior of the dielectric constant epsilon(T). The results are treated within the framework of the coupled SM and transverse optic (TO1) mode and the temperature dependence of the SM frequency at q=0.075a* is determined. The parameters of the SM are consistent with the earlier estimates and the frequency exhibits a minimum near the Burns temperature (approximate to650 K).