Improved sinterability and microwave dielectric properties of [Zn _0.5 Ti _0.5 ] ³⁺ ‐doped ZnAl ₂ O ₄ spinel solid solution

Abstract

Abstract Low‐permittivity ZnAl 2‐ x (Zn 0.5 Ti 0.5 ) x O 4 ceramics were synthesized via conventional solid‐state reaction method. A pure ZnAl 2 O 4 solid‐state solution with an Fd‐3m space group was achieved at x ≤ 0.1. Results showed that partial substitution of [Zn 0.5 Ti 0.5 ] 3+ for Al 3+ effectively lowered the sintering temperature of the ZnAl 2 O 4 ceramics and remarkably increased the quality factor ( Q × f ) values. Optimum microwave dielectric properties ( ε r = 9.1, Q × f = 115,800 GHz and τ f = −78 ppm/°C) were obtained in the sample with x = 0.1 sintered at 1400°C in oxygen atmosphere for 10 h. The temperature used for the sample was approximately 250°C lower than the sintering temperature of conventional ZnAl 2 O 4 ceramics.