Frequency and Temperature Dependence of Dielectric and Electrical Properties of Sn-Doped Lead Calcium Iron Niobate.

Sn-substituted lead calcium iron niobate specimens with general formula (PbCa)(FeNb)SnO with 0.00 ≤ y ≤ 0.15 in steps of 0.03 have been synthesized using a two-stage method. The x-ray diffraction patterns for all the synthesized samples reveal a perovskite structure with pseudocubic symmetry. A small amount of pyrochlore phase was obtained along with the perovskite phase, decreasing with increasing Sn content up to y = 0.09. The temperature and frequency dependence of the dielectric and electrical properties of Sn-substituted lead calcium iron niobate were studied. Two dielectric anomalies were observed in ε- T plots for all the samples due to generation of oxygen vacancies. The temperature coefficient of relative permittivity, τ, decreased with increasing Sn content. The single, semicircular arc observed in Nyquist plots suggests a single relaxation process. The activation energies obtained from the temperature dependence of the relaxation time and grain resistance were found to be approximately comparable. [ABSTRACT FROM AUTHOR]