Effect of MgO and Y2O3 additions on modifying the dielectric constant-temperature (K–T curve) properties of the base-metal-electroded BaTiO3 materials was systematically studied. The absolute value of (ΔC/C)−55 °C and (ΔC/C)125 °C can be reduced, i.e., be moved upward, by incorporating large enough concentration of MgO and Y2O3 additives into the BaTiO3, such that the K–T characteristics of the materials meet the X7R specification. The Y2O3 doping is more effective than the MgO doping in moving the (ΔC/C)−55 °C and (ΔC/C)125 °C upward, which can be attributed to the fact that Y2O3 species addition flattens the K–T curves without shifting the Curie point of the materials. However, the proportion of Y2O3 incorporated into the materials should exceed the solubility of the BaTiO3 materials such that the Y2O3 species can reside at the grain boundary region, forming a core-shell microstructure.
Journal of the European Ceramic Society 24(6), pp.1479-1483