Structural, Dielectric and Pyroelectric Properties of Praseodymium Based Complex Tungsten Bronze Ferroelectrics.

This paper highlights the structural, dielectric and pyroelectric properties of two complex tungsten bonze ceramics (K2Pb2Pr2W2Ti4Nb4O30and K2Pb2Pr2W2Ti4Ta4O30) which were prepared by high temperature mixed oxide method. Room temperature X-ray structural analysis confirms the formation of the compounds in single phase. SEM micrographs show uniform distribution of densely packed rod like grains. Variation of dielectric parameters with temperature and frequency shows the phase transition at 350°C and 426°C for the respective samples. Temperature dependent hysteresis loop confirms the existence of ferroelectricity in the materials. The current variation with voltage at different temperatures shows the semiconductor like behaviour of the materials. The temperature dependent dc conductivity follows the Arrhenius equation, and reveals the negative temperature coefficient of resistance (NTCR) behaviour of the materials. The current (for a fixed voltage) variation with temperature shows that the materials have high pyroelectric co-efficient and figure of merit, thus making them useful for pyroelectric sensors. [ABSTRACT FROM AUTHOR]