Enhanced tetragonality in (x)PbTiO3-(1−x)Bi(Zn1∕2Ti1∕2)O3 and related solid solution systems

The solid solutions (x)PbTiO3-(1−x)Bi(Zn1∕2Ti1∕2)O3, (x)PbTiO3-(1−x)Bi(Zn1∕2Zn1∕2)O3, and (x)PbTiO3-(1−x)Bi(Zn1∕2Sn1∕2)O3, have been examined by x-ray diffraction, dielectric measurements, and thermal analysis. Unlike most PbTiO3-based solid solutions, these systems show enhanced tetragonality with substitution for PbTiO3. In particular, the (x)PbTiO3-(1−x)Bi(Zn1∕2Ti1∕2)O3 system exhibits a high c∕a ratio of 1.11 for x=0.60. Accordingly, the Curie temperature (TC) also increases, exceeding 700°C at the same composition. It is proposed that PbTiO3-Bi(B)O3-type solid solutions which contain only highly polarizable cations on the B site are likely to exhibit similar enhancements in tetragonality and TC.