Phase transition and conduction mechanism of rare earth based tungsten-bronze compounds

The polycrystalline materials (Li2Pb2R2W2Ti4Nb4O30 (R = Y, Eu)) of tungsten-bronze structural family have been synthesized using a high-temperature solid-state reaction (mixed-oxide) technique. The formation of the single phase compounds was checked using preliminary X-ray structural data/pattern. The nature and distribution of grains in the samples in the scanning electron micrographs (SEM) confirm the good quality of the samples used for electrical characterization. The phase transition (ferroelectric-paraelectric) in the materials was established through the detailed studies of dielectric, electric polarization and pyro-electric properties. Studies of pyroelectric properties show that the materials have reasonably high figure of merit useful for pyroelectric detector. The nature of frequency dependence of ac conductivity suggests that the materials obey Jonscher's universal power law. (C) 2012 Elsevier B.V. All rights reserved.