The effects of $80Bi_2O_3-20$[XCaO-(1-X)BaO] oxide melt infiltration on the microstructure and dielectric properties of $SrTiO_3$-based GBBLC (Grain Boundary Barrier Layer Capacitor) have been investigated. Strontium titanate powder compacts containing 0.2 mol% $Nb_2O_5$ were sintered at 1480℃ for 5h in $95N_2-5H_2$ atmosphere to make semiconducting $SrTiO_3$ grain. The liquid infiltrants were infiltrated into sintered $SrTiO_3$ at 1300℃ in air. When the value X was 0, 0.2, 0.7 or 1.0, grain boundary migration occurred, forming a new solid solution containing solute species. The migration distance increased linearly with the liquid infiltration time. In contrast, when X=0.5, no interface migration was observed. The driving force for the grain boundary migration has been explained in terms of the coherency strain energy stored at solid/liquid interface by solute atoms diffusion into grains. With decrease in migration distance, the effective dielectric constant increased and showed the highest value for specimen without interface migration. The specimen without migration also showed low tangent loss and low dependence of dielectric property on temperature. The considerable improvement in dielectric properties of the specimen without migration was attributed to minimum thickness of improved properties of an oxidation layer and insulating $BaO-CaO-Bi_2O_3$ oxide film.
