Effects of MgO and Rare-Earth Oxides (Y2O3, Yb2O3, Dy2O3) on the Structural Characteristics and Electrical Properties of BaTiO3

This study investigated the impact of MgO and rare-earth oxides (Y2O3, Yb2O3, and Dy2O3) on the structural characteristics and electrical properties of BaTiO3. Specimens sintered at 1350 °C for durations ranging from 1 to 5 h in air exhibited a single phase of BaTiO3 with a tetragonal structure. This was observed for pure BaTiO3 and specimens co-doped with MgO-Y2O3 and/or MgO-Dy2O3. However, a pseudo-cubic structure of BaTiO3 was detected for specimens doped with MgO or co-doped with MgO-Yb2O3. The unit-cell volume of the sintered specimens was found to be dependent on the type of substitution ion for the A/B site of BaTiO3 (ABO3). The dielectric constant (εr) of the sintered specimens decreased with the substitution of MgO and rare-earth oxides due to a decrease in tetragonality (c/a). The electrical resistivities of the sintered specimens were influenced not only by their microstructural characteristics but also by the secondary phases of the sintered specimens. The BaTiO3 specimens co-doped with MgO-Yb2O3 and/or doped with MgO met the EIA X7R and X8R specifications (−55 to 125~150 °C, ΔC/C = ±15% or less), respectively.