Synthesis and properties of TiO2 added NiNb2O6 microwave dielectric ceramics using a simple process

TiO2 added NiNb2O6 ceramics produced using a reaction-sintering process were investigated. Pure columbite NiNb2O6 could be obtained without TiO2 addition. With 30 and 40 mol% TiO2 addition, a phase with the same structure Ni0.5Ti0.5NbO4 formed. Grain growth was easier in pellets with 30 and 40 mol% TiO2 additions than in the NiNb2O6 pellets. Microwave dielectric properties: epsilonr = 20.7, Qxf = 19800 GHz (at 9 GHz) and tauf = -31.9 ppm/C were obtained for NiNb2O6 pellets sintered at 1300 C/2 h. epsilonr about 45, Qxf = 5400-7700 GHz (at 6 GHz) and tauf about 73 ppm/C were obtained in pellets with 30 mol% TiO2 addition. epsilonr about 50, Qxf = 3800-5700 GHz (at 6 GHz) and tauf about 99 ppm/C were obtained in pellets with 40 mol% TiO2 addition.