The influence of Cu substitution on the microwave dielectric properties of BaZn2Ti4O11 ceramics

BaZn2−xCuxTi4O11 (x = 0.00–0.14) ceramics were prepared by the conventional solid-state reaction technique and the effects of Cu2+ substitution on the crystal structure, microstructure and microwave dielectric properties of BaZn2Ti4O11 ceramics were investigated. The substitution of Cu2+ for Zn2+ in BaZn2Ti4O11 phase caused the decrease of the lattice parameters, and the adding of CuO formed the liquid-phase sintering mechanism, which effectively improved the densification process and lowered the sintering temperature. More importantly, the decrease of the lattice parameters was likely to make the bonding force and the crystal structure to become stronger, and the substitution of Cu2+ could restrain the lost of oxygen or the formation of Ti3+ ions when sintering BaZn2−xCuxTi4O11 ceramics at 1140–1210 °C in air, thereby, both of these two reasons significantly increased the Q × f value form 10,600 GHz at x = 0.00–51,400 GHz at x = 0.02. At last, BaZn1.98Cu0.02Ti4O11 was sintered well at 1190 °C for 2.5 h in air and showed good microwave dielectric properties: εr = 29.5, Q × f = 51,400 GHz and τf = −33.7 ppm/°C.

► Microwave dielectric properties of BaZn2−xCuxTi4O11 ceramics were investigated.
► The substitution of Cu for Zn decreased the lattice parameters of BaZn2Ti4O11.
► The substitution restrained the formation of Ti3+ ion in BaZn2−xCuxTi4O11 ceramics.
► Both of these two reasons increased the Q × f value of BaZn2−xCuxTi4O11 ceramics.