Bond ionicity, lattice energy, bond energy and microwave dielectric properties of ZnZr(Nb1−xAx)2O8 (A = Ta, Sb) ceramics

Abstract

The dependence of microwave dielectric properties on the structural characteristics of ZnZr(Nb_1−xA_x)₂O₈ (A = Ta, Sb) (0 ≤ x ≤ 0.10) ceramics is investigated. All the compounds were prepared by a conventional solid-state reaction method and analyzed via multiphase structure refinement. The diffraction patterns of ZnZr(Nb_1−xA_x)₂O₈ (A = Ta, Sb) show the monoclinic wolframite structure of ZrZrNb₂O₈ which consists of an oxygen octahedron, with the Nb ion in the center of the oxygen octahedron. For the ZnZr(Nb_1−xA_x)₂O₈ (A = Ta, Sb) ceramics, the dielectric constant (ε_r) decreased with the decrease in Nb-site bond ionicity. The quality factor (Q × f) of ZnZr(Nb_1−xSb_x)₂O₈ ceramics was found to be the highest (89 400 GHz), which is explained in terms of the average of the Nb-site lattice energy. With the decrease in the bond energy of the Nb-site, the temperature coefficient of resonant frequency (|τ_f|) value increased. The substitution of A⁵⁺ (A = Ta, Sb) for Nb⁵⁺ effectively influences the microstructure and microwave dielectric properties of ZrZrNb₂O₈ ceramics.