$SrTiO_3$ grain boundary barrier layer capacitors (GBBLC) have been prepared by using solid state diffusion of $BaTiO_3-CaTiO_3$ and their electrical properties characterized. Sintered $SrTiO_3$ samples doped with $Nb_2O_5$ have been packed with $BaTiO_3-CaTiO_3$ powder mixtures and reoxidized at 1000℃-1200℃ for 1h. During the reoxidation treatment, Ba and Ca ions diffuse into grain boundaries of $SrTiO_3$ and form $(Ba,Ca)TiO_3$ layer. With increasing the reoxidation temperature, the effective dielectric constant decreases possibly because of an increase in the thickness of reoxidized layer. The dielectric constant of the Ba-Ca doped samples is lower by an order of one than that of standard undoped samples. Nevertheless, the doped samples show lower temperature coefficient, better frequency stability and higher electrical resistance, suggesting a possibility of commercial application.
