Temperature dependence of the generalized vibrational density of states ofsodium bismuth titanate in the ferroelectric phase

This paper describes studies of relaxer ferroelectric Na1/2Bi1/2TiO3 (NBT) by inelastic incoherent neutron scattering at temperatures from 50 to 300 K . Experimental time-of-flight spectra were recalculated into the generalize d vibrational density of states (VDOS) function in terms of one-particle in coherent approximation and compared with the behavior of Raman spectra. It is shown that the VDOS of NET in the ferroelectric phase has nontrivial tem perature dependence. The relation between the temperature dependence of VDO S and the instability of the NET crystalline lattice below room temperature is discussed. (C) 2000 Published by Elsevier Science Ltd.