Dielectric properties and high-temperature dielectric relaxation of tungsten-bronze structure ceramics BaGdFeNbTaO.

BaGdFeNbTaO was synthesized by a standard solid-state technique, which adopts a tetragonal filled tungsten bronze structure and exhibits paraelectric nature at room temperature. The dielectric temperature coefficient of BaGdFeNbTaO at 1 MHz is 147 ppm °C AC impedance plots were used as tools to analyze the electrical behavior of the sample as a function of frequency at different temperatures. The conduction is a thermally activated process with activation energy ~1.30 eV. The frequency-dependent maxima in the imaginary part of impedance are found to obey an Arrhenius law with activation energy ~1.34 eV. Such a value of activation energy suggests the existence of a relaxation mechanism (a conductive process), which may be interpreted by an ion hopping between neighboring sites within the crystalline lattice. [ABSTRACT FROM AUTHOR]