Microstructure and dielectric properties of BaTiO3–(Bi0.5Na0.5)TiO3–NiNb2O6 ceramics

Abstract

0.9BaTiO3–0.1(Bi0.5Na0.5)TiO3–x mol% NiNb2O6 (x = 0, 0.5, 1.0, 1.5, 2.0, 2.5) ceramics were prepared through traditional solid-state reaction method. The effects of NiNb2O6 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 NiNb2O6 doping amount. Ba11(Ni,Ti)28O66+x and Nb2O5 were detected in the X-ray diffractions patterns. The Curie point Tc increased slightly with the increase of NiNb2O6 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 NiNb2O6 concentration. Dielectric temperature stability of 0.9BaTiO3–0.1(Bi0.5Na0.5)TiO3 ceramics greatly depended on NiNb2O6 content. The optimum dielectric properties meeting the X9R specification were obtained in the composition of 0.9BaTiO3–0.1(Bi0.5Na0.5)TiO3 with 1.5 mol% NiNb2O6 sintered at 1200 °C, er = 1652 and tanδ = 1.8% at room temperature.