Dielectric properties and relaxation of SrBi 2(Nb 0.25Ta 0.75) 2O 9 ceramic at RF frequency

Abstract

The dielectric properties and relaxation of the SrBi 2(Nb 0.25Ta 0.75) 2O 9 ceramic were investigated from 3 to 300 MHz using frequency domain measurement by an impedance spectroscopy. Our results show that the dielectric relaxation of the ceramic can be understood in terms of power law dependence known as the Curie–von Schweidler law. It is assumed that defects, Schottkey jumps of electrons between localized states and the motions of ions play an important role in the dielectric properties and relaxation of the ceramic. The ceramic has large relative permittivity ( ε r ∼117 at 300 MHz), low dielectric loss (tanδ e <0.018 at 300 MHz) and small dispersion (<3% decrease in ε r from 3 to 300 MHz). The Curie temperature of the ceramic is very high (∼370 °C), implying that it has a small temperature coefficient. Hence the SrBi 2(Nb 0.25Ta 0.75) 2O 9 ceramic is a potential candidate for microwave applications.