Abstract
Effect of MgO and Y 2 O 3 additions on modifying the dielectric constant-temperature (K-T curve) properties of the base-metal-electroded BaTiO 3 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 Y 2 O 3 additives into the BaTiO 3 , such that the K-T characteristics of the materials meet the X7R specification. The Y 2 O 3 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 Y 2 O 3 species addition flattens the K-T curves without shifting the Curie point of the materials. However, the proportion of Y 2 O 3 incorporated into the materials should exceed the solubility of the BaTiO 3 materials such that the Y 2 O 3 species can reside at the grain boundary region, forming a core-shell microstructure. © 2003 Published by Elsevier Ltd.