Control of structure uniformity in ceramic lithium tantalate with a different stoichiometry via Raman spectra

Lithium tantalate (LT) ceramics of various stoichiometry in the concentration range 48.5-51.4 mol% Li2O has been synthesized. The dependence of microstructure on the ceramics composition has been studied. Ceramic samples of LT of composition 48.5, 48.7, 49.0, 49.1, 49.3, 49.5, 50.5, 50.8, 51.0, 51.2 and 51.4 mol% Li2O have been investigated by Raman spectroscopy. Weak bands have been observed for the first time in the spectral region of 1000-2500 cm(-1) of all the studied samples. Regular Raman bands have been detected in the fundamental vibrations of crystal lattice in the 150-900 cm(-1) region. The bands are characteristic of single crystal states. Theoretical modeling suggests that the appearance of a second-order spectrum may be due to the small size of crystallites in ceramic samples. These investigations have helped to develop a method for controlling the structural uniformity of LT ceramic samples using Raman spectra.