Influence of inverse spinel structured CuGa 2 O 4 on microwave dielectric properties of normal spinel ZnGa 2 O 4 ceramics

Spinel Zn 1‐ x C u x Ga 2 O 4 ( x  =   0‐0.15) ceramics were prepared by the conventional solid‐state method. Only a single phase was indexed in all samples. The continuous lattice contraction of ZnGa 2 O 4 unit cell was caused by Cu 2+ substitution, and the lattice parameter shows a linear correlation with the content of Cu. The refined crystal structure parameters suggest that Cu 2+ preferentially occupies the octahedron site, and the degree of inversion of Zn 1‐ x Cu x Ga 2 O 4 ( x  =   0‐0.15) ceramics almost equals to the content of Cu 2+ . The relative intensity of A* 1g mode in Raman spectra confirm that the degree of inversion climbed with the growing content of Cu 2+ . The experimental and theoretical dielectric constant of Zn 1‐ x Cu x Ga 2 O 4 ceramics fit well. Zn 1‐ x Cu x Ga 2 O 4 ( x  =   0.01) ceramics sintered at 1400°C for 2 h exhibited good microwave dielectric properties, with ε r  = 9.88, Q  ×  f  =   131,445 GHz, tan δ = 6.85 × 10 −5 , and τ f   = −60 ppm/°C.