Synthesis and Electrical Properties of KF-Doped BaTiO₃ Ceramics

Abstract

KF-doped barium titanate ceramics, Ba 1- x K x TiO 3- x F x (KF-BT/ x : 0≦ x ≦0.15), were fabricated by spark plasma sintering (SPS) using fine particles prepared by a sol–gel method. We measured the dielectric and piezoelectric properties of the SPS ceramics after annealing in an O 2 gas flow at 1273 K. The dielectric constant and the piezoelectric constant d 33 were enhanced in KF-BT/0.10, as found in the single crystals, because the composition of x =0.10 locates near the tricritical point (TCP). However, some different behaviors from those of the single crystals were found; in particular, T C of the ceramic forms is much higher than that of the crystalline forms, and the difference becomes marked with increasing x . We consider that the evaporation of F - , which occurs during the O 2 annealing process, markedly increases T C .