Evidence of pseudocubic structure in sol-gel derived Pb1−xCaxTiO3 (x=0.35–0.48) ceramic by dielectric and Raman spectroscopy

Calcium doped lead titanate (Pb1−xCaxTiO3) ceramics with varying stoichiometry (x=0–0.55) have been prepared using sol-gel derived powder. The x-ray diffraction shows the transformation of crystallographic structure from tetragonal to cubic at x∼0.35. Raman spectroscopy and temperature dependent dielectric studies were made on all prepared ceramic samples. A continuous shift in the phase transition temperature toward lower temperature was observed with increase in x. The presence of soft phonon mode in the Raman spectra, along with phase transition temperature, gives the evidence for the formation of pseudocubic structure of Pb1−xCaxTiO3 ceramics for higher values of x>0.35.