Structural, dielectric and electrical properties of dysprosium based new complex electroceramics

The polycrystalline sample of K2Pb2Dy2W2Ti4Nb4O30 was synthesized by high-temperature solid-state reaction method (calcinations temperature similar to 1,050 A degrees C and sintering temperature similar to 1,075 A degrees C). The phase formation of the desired compound was confirmed by preliminary X-ray structural analysis. The scanning electron micrograph shows uniform plate and rod like grain distribution throughout the surface of the sample without much pores. Detailed studies of the nature of (1) variation of dielectric parameters with temperature (27-480 A degrees C) and frequency (1 kHz-5 MHz) and (2) polarization (at three different temperatures) confirmed the existence of ferroelectricity in the material, with phase transition occurring at 316 A degrees C. The temperature dependence of electrical parameters (impedance, modulus, conductivity, etc.) of the material exhibits a strong correlation between its micro-structure (i.e., bulk, grain boundary, etc.) and electrical properties. The nature of temperature dependent dc conductivity follows the Arrhenius equation, and reveals the negative temperature coefficient of resistance (NTCR) behaviour of the material. The material obeys Jonscher's universal power law which is evident from the graphs of frequency dependence of ac conductivity.