Synthesis and Electrical Properties of KF-Doped BaTiO3 Ceramics

Abstract

KF-doped barium titanate ceramics, Ba1-xKxTiO3-xFx (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 O2 gas flow at 1273 K. The dielectric constant and the piezoelectric constant d33 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, TC 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 O2 annealing process, markedly increases TC.