Microwave dielectric properties of (A2+ 1/3B5+ 2/3)0.5Ti0.5O2 (A2+ = Zn, Mg, B5+ = Nb, Ta) ceramics

Dielectric properties of (A²⁺ _1/3B⁵⁺ _2/3)_0.5Ti_0.5O₂ (A²⁺ = Zn, Mg, B⁵⁺ = Nb, Ta) (A²⁺ = Zn, Mg, B⁵⁺ = Nb, Ta) ceramics were investigated at microwave frequencies. A single phase with tetragonal rutile structure was obtained through the entire compositions. Dielectric properties were strongly dependent on the structural characteristics. The specimens with B⁵⁺ = Nb showed a larger dielectric constant than those with B⁵⁺ = Ta due to the decrease of bond valence. Quality factors (Qf) of the specimens with B⁵⁺ = Ta were larger than those with B⁵⁺ = Nb. Temperature coefficient of the resonant frequencies (TCF) of (Zn_1/3Nb_2/3)_0.5Ti_0.5O₂ was larger than that of (Mg_1/3Ta_2/3)_0.5Ti_0.5O₂. These results could be attributed to the changes of the temperature coefficient of dielectric constant and the degree of oxygen octahedral distortion.