Correlations between microwave dielectric properties and crystal structures of Sb-doped Co0.5Ti0.5NbO4 ceramics

Abstract

Co0.5Ti0.5Nb1-xSbxO4 (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) ceramics with low dielectric losses were fabricated by the conventional solid-state reaction method. A single-phase tetragonal rutile structure with a superlattice diffraction peak was observed. The temperature coefficient of resonant frequency (τf) decreased with an increase in oxygen octahedron distortion. The quality factor (Q×f) was increased owing to the enhanced cation ordering, which reduced the lattice energy and internal stress of the oxygen octahedron. Sb3+ was transformed into Sb5+, while the transformation of Co2+ to Co3+ was inhibited. The as-prepared Co0.5Ti0.5Nb0.5Sb0.5O4 ceramic exhibited εr of 38, Q × f of 32,047 GHz, and τf of 32.6 parts-per-million/°C.