Microstructure and dielectric properties of BaTiO 3 –(Bi 0.5 Na 0.5 )TiO 3 –NiNb 2 O 6 ceramics

0.9BaTiO 3 –0.1(Bi 0.5 Na 0.5 )TiO 3 –x mol% NiNb 2 O 6 (x = 0, 0.5, 1.0, 1.5, 2.0, 2.5) ceramics were prepared through traditional solid-state reaction method. The effects of NiNb 2 O 6 doping on the dielectric properties and the microstructure of ceramics were investigated systematically. The results showed that the grain size of the ceramics decreased with the increase of NiNb 2 O 6 doping amount. Ba 11 (Ni,Ti) 28 O 66+x and Nb 2 O 5 were detected in the X-ray diffractions patterns. The Curie point T c increased slightly with the increase of NiNb 2 O 6 doping amount. It was interesting to find that the dielectric constant at low temperature of the ceramics first increased and then decreased with the increase of NiNb 2 O 6 concentration. Dielectric temperature stability of 0.9BaTiO 3 –0.1(Bi 0.5 Na 0.5 )TiO 3 ceramics greatly depended on NiNb 2 O 6 content. The optimum dielectric properties meeting the X9R specification were obtained in the composition of 0.9BaTiO 3 –0.1(Bi 0.5 Na 0.5 )TiO 3 with 1.5 mol% NiNb 2 O 6 sintered at 1200 °C, ε r = 1652 and tan δ = 1.8% at room temperature.