Density of vibration states and ferroelectric properties of complex perovskites

We studied the effect of temperature on density of vibrational states of model complex perovskites PbMg1/3Nb2/3O3 (PMN), PbMg1/3Ta2/3O3 (PMT), and BaMg1/3Ta2/3O3 (BMT) by inelastic neutron scattering. It has been found that PMN and PMT relaxor ferroelectrics exhibit an anomalous temperature evolution of the density of vibrational states G(E), while G(E) in the BMT compound does not demonstrate any temperature evolution. It is shown that there is a correlation between the temperature behaviors of the dielectric response and vibrational spectra of all the complex perovskites studied. Possible reasons for variation in G(E) in these materials are discussed. (C) 2003 American Institute of Physics.