Structural and Raman analyses of the (A_1-xPb_x) TiO₃(A=Ca, Sr, Ba) perovskites

Powder X-ray diffraction and laser Raman spectroscopy were used to study systematically the structural and dynamical changes in three series of plumbous perovskites of composition Ba_1-xPb_xTiO₃Sr_1-xPb_xTiO₃ and Ca_1-xPb_xTiO₃ with 0 <x < 1. For the latter two series prominent phase transitions were found at x ca. 0.5 and 0.55, respectively. As well, Raman spectroscopy provided the means to track the evolution of active vibrational modes characteristic of the end-members across the doping range. The temperature dependence of the Raman spectra showed that the ferroelectric transition temperature of the (Ca, Pb) series can be tailored over a wide temperature range by judicious doping.