Double phase transitions in K2Pb2Sm2W2Ti4Nb4O30 ferroelectrics

This paper reports about the double phase transition (at 315 and 366 A degrees C) in the polycrystalline sample of K2Pb2Sm2W2Ti4Nb4O30 prepared by a high-temperature solid-state reaction technique. The calcination temperature was decided based on thermogravimetry analysis. Room temperature X-ray structural analysis confirms the formation of a single phase compound. The surface morphology recorded by scanning electron microscope exhibits a uniform grain distribution with high density. Detailed studies on the nature of variation (1) of dielectric parameters with temperature, and (2) polarization with temperature confirmed the existence of ferroelectricity in the material at room temperature. The temperature dependence of dc conductivity shows a typical Arrhenius behavior. The frequency dependence of ac conductivity suggests that the material obeys Jonscher's universal power law. The variation of current with temperature shows that the material has high pyroelectric co-efficient and figure of merit, thus making it useful for pyroelectric sensors.