B-site Dopant Effect on the Thermal Expansion in the (1-x)PbTiO3-xBiMeO3 Solid Solution (Me = Fe, In, Sc)

摘要

The (l-x)PbTiO3-xBiMeO3 (Me = Fe, In, Sc) solid solutions were prepared and investigated using high-temperature X-ray diffraction for the B-site dopant effect on their thermal expansion behaviors. Compared with PbTiO3, the negative thermal expansion of (l-;c)PbTiO3-.*:BiFeO3 was enhanced, whereas that of (l-x)PbTiO3-jrBiInO3 was a little weakened and was much weakened in (l-x)PbTiO3-xBiScO3. An empirical linear correlation between the average effective radius of the B-site cations and the unit cell volumes at Curie point of the solid solutions was concluded. The relationship was also observed in other PbTiO3-BiMeO3-type solid solutions and was supposed to be widely useful in predicting the thermal expansion coefficient of compounds of this sort. Above the Curie point, the unit cell volumes of the compounds were determined by the radii of the doped B-site cations. The weaking and vanishing of the lattice distortion caused by spontaneous polarization displacements was proved by Raman scatting spectrum, which supported the relationship in the lattice dynamic aspect.