Structural, electrical and dielectric properties of Bi1.5Zn0.92Nb1.5−xTaxO6.92 pyrochlore ceramics

The micro-structural, compositional, temperature dependent dielectric and electrical properties of the Bi1.5Zn0.92Nb1.5−xTaxO6.92 solid solution has been investigated. The increasing Ta content from 0.2 to 1.5 caused; single phase formation, a pronounced grain size reduction from ∼7.0 to 2.5 μm, sharp decrease in the dielectric constant from 198 to 88 and an increase in the electrical conductivity from 3.16 × 10−10 to 5.0 × 10−9 (Ω cm)−1, respectively. The temperature dependent dielectric constant which is found to be frequency invariant in the frequency range of (0.0–2.0 MHz) exhibited a sharp change in the temperature coefficient of dielectric constant at a (doping independent) critical temperature of 395 K. The analysis of the measured data reflects a promising future for this type of pyrochlore to be used in high voltage passive device applications.