Crystal structure and microwave dielectric properties of (Zn1−xCox)TiNb2O8 ceramics

Abstract The crystal structure and microwave dielectric properties of (Zn 1− x Co x )TiNb 2 O 8 ceramics have been investigated. The results showed that the (Zn 1− x Co x )TiNb 2 O 8 ceramics contained two main phases: (Zn,Co)TiNb 2 O 8 phase and (Zn,Co) 0.17 Nb 0.33 Ti 0.5 O 2 phase. The microwave dielectric properties of the (Zn 1− x Co x )TiNb 2 O 8 ceramics were strongly affected by the change of crystal structure of each phase. The (Zn 1− x Co x )TiNb 2 O 8 ( x  = 0.1, 0.2, 0.3, 0.4) ceramics were sintered at temperatures ranging from 1025 to 1125 °C for 4 h. With the increase of Co content, the amount of (Zn,Co) 0.17 Nb 0.33 Ti 0.5 O 2 phase increased, resulting in the increase of the dielectric constant ( e r ), decrease of the Q  ×  f value and the temperature coefficient of resonant frequency ( τ f ) moving to the positive direction. The excellent microwave dielectric properties of e r  = 35.93, Q  ×  f  = 35,125 GHz, τ f  = 0 ppm/°C were obtained for the (Zn 1− x Co x )TiNb 2 O 8 ceramics ( x  = 0.3) sintered at 1075 °C for 4 h. The relatively low sintering temperature (