Thermal, structural and optical properties of Pb1−x La x TiO3 prepared using modified sol–gel route

Abstract

Abstract La doped lead titanate ceramic compositions Pb1−x La x TiO3 (PLT) for x = 0.0, 0.05, 0.1, 0.2 and 0.3 were synthesized by an acrylic acid modified sol-gel route. The microstructure, surface morphology, and optical properties of the resulting compositions were studied by using TGA, X-ray diffraction, Raman Spectroscopy, and UV–Vis spectroscopy. It was found that the acrylic acid acts as a strong gelling agent and the organic residue gets removed completely below 450 °C. Very smooth ceramic powders characterized by single perovskite phase were obtained. A reduction in the tetragonality ratio from 1.0698 to 1.0033 was observed with increasing La content from x = 0.0 to x = 0.3. The effect of reduced tetragonality was corroborated by the peak shift of soft modes in Raman spectra and approximately 2 cm−1 downshift of E(TO1) mode was observed for each atomic weight percent La addition in lead titanate. The average grain size was found decreasing marginally with the increasing La content in PLT. Using the UV–vis data, a slight but systematic increase in the direct absorption edge (band gap) from 3.155 eV to 3.234 eV was observed with increasing La content in the PLT compositions.