Effect of V2O5 on the sintering behavior, microstructure, and electrical properties of (Na0.5K0.5)NbO3 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.