Effect of V 2 O 5 on the sintering behavior, microstructure, and electrical properties of (Na 0.5 K 0.5 )NbO 3 ceramics

Well-sintered (Na 0.5 K 0.5 )NbO 3-x mol% V 2 O 5 ceramics (abbreviated as NKN-V) with fine electrical properties were successfully prepared by conventional solid-state reaction through the careful control of processing conditions. The sintering behavior, phase structure, and electrical properties of the V 2 O 5 -doped NKN ceramics were investigated. Results show that when the V 2 O 5 content is 0.6 mol%, the NKN ceramics attained the maximum density of 4.46 g/cm 3 (about 98.9% of the theoretical density) at 1060degC, and therefore possessed enhanced electrical properties. But when the V 2 O 5 content continued increasing, the density decreased. The secondary phase (Na 2 V 6 O 16 ) could be detected by XRD analysis in all samples except x = 0 mol%. The Curie temperature of the NKN-based materials was found to decrease with the increase of V 2 O 5 . The dielectric properties of NKN ceramics doped with 0.6 and 0.9 mol% V 2 O 5 were better than that of pure NKN ceramics. In addition, annealing treatment was proved to be an effective technique for improving dielectric properties and reducing the leakage current density.