Electrical and dielectric studies of substituted holmium based pyrochlore zirconates nanomaterials

Abstract

The effects of Ge4+ cation substitution on the structure, morphology, electrical and dielectric properties of rare earth pyrochlore oxides (Ho2Zr2-xGexO7, 0.00 ≤ x ≤ 1.0) were investigated. The pyrochlore oxides were prepared by the microemulsion method. The XRD data Ge+4 substituted Ho2Zr2-xGexO7 reveal a cubic structure. Room temperature DC electrical resistivity increases on increasing the Ge4+ contents. The value of exponent ‘n’ calculated from the plot of log(σ) versus log(ω) ranges 0.78–0.95 suggested that the conduction phenomena in the studied samples pursue hopping conduction. Nyqiust plot (cole–cole plot) was used to study relaxation phenomenon in the material. The visualization of semicircles in plot represent that grain boundary occupies small volume. The dielectric loss with frequency shows resonance peaks. The dielectric losses were stable below 1.3 GHz. Such frequency independent characteristic of the high dielectric constants Ho2Zr2-xGexO7 ceramics and their low dielectric losses make them more attractive in the applications of multilayer ceramic capacitors and resonators. The increase in resistivity with substitution makes these materials suitable for microwave devices.