Dielectric and crystallographic study of the lead magnotantalate relaxor

The complex perovskite Pb(Mg1/3Ta2/3)O3 is one of the first relaxor ferroelectric compounds that was investigated. The present study reports some new important data of dielectric properties and structure characteristics. A Vogel-Fulcher behavior is observed for the frequency dependence of Tmax with a freezing temperature Tf=144K. Dielectric measurements under high electric field show that the dielectric constant decreases as the field increases, but Tmax remains unchanged. The x-ray crystallographic study reveals a cubic structure down to liquid nitrogen temperature. The temperature dependence of the cell parameter is determined and the cluster nucleation temperature is thus estimated to be about 573K. The difference in relaxor behavior between Pb(Mg1/3Ta2/3)O3 and Pb(Mg1/3Nb2/3O3 is discussed.