Effect of MgO Doping on the Phase Transformations of BaTiO3

The successive phase transformations in MgO‐doped BaTiO3 were studied. Upon MgO doping, dielectric anomalies corresponding to lower phase transformations were broadened and depressed, while an anomaly for a cubic–tetragonal transformation remained and shifted to a lower temperature. XRD peak splitting upon tetragonality of BaTiO3 was decreased, and the peaks exhibited abnormally broadened profiles which are different from the one for cubic BaTiO3 above Tc. Raman spectroscopy revealed the existence of orthorhombic phase at room temperature for the solid solution with 0.5 mol% or more MgO. The temperature dependence of the Raman spectrum showed that orthorhombic and rhombohedral phases in MgO‐doped BaTiO3 were stabilized at higher temperatures than pure BaTiO3.