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

The crystal structure and microwave dielectric properties of (Zn-1 Co-x(x))TiNb2O8 ceramics have been investigated. The results showed that the (Zn-1 Co-x(x)) TiNb2O8 ceramics contained two main phases: (Zn,Co)TiNb2O8 phase and (Zn,Co)(0.17)Nb0.33Ti0.5O2 phase. The microwave dielectric properties of the (Zn-1 Co-x(x))TiNb2O8 ceramics were strongly affected by the change of crystal structure of each phase. The (Zn-1 Co-x(x))TiNb2O8 (x = 0.1, 0.2, 0.3, 0.4) ceramics were sintered at temperatures ranging from 1025 to 1125 degrees C for 4 h. With the increase of Co content, the amount of (Zn,Co)(0.17)Nb0.33Ti0.5O2 phase increased, resulting in the increase of the dielectric constant (epsilon(r)), decrease of the Q x f value and the temperature coefficient of resonant frequency (tau(f)) moving to the positive direction. The excellent microwave dielectric properties of epsilon(r) = 35.93, Q x f = 35,125 GHz, tau(f) = 0 ppm/degrees C were obtained for the (Zn1 xCox) TiNb2O8 ceramics (x = 0.3) sintered at 1075 degrees C for 4 h. The relatively low sintering temperature (<1080 degrees C) and high dielectric properties in microwave range make these ceramics promising for application in electronics. (C) 2012 Elsevier B.V. All rights reserved.