Far infrared properties of PLZT ceramics

Far infrared and mid infrared reflectivity measurements have been made of lead titanate zirconate (PLZT) ceramics at room temperature in the frequency range 40–1500 cm-1. Kramers-Krönig analysis and a fitting procedure based on a four parameter model of the spectrum, determined the infrared active transverse and longitudinal optical modes and their damping factors. Group theory analysis has been done and the number of experimentally observed infrared active modes was compared with the theoretical prediction. Three ionic oscillators for a cubic perovskite Pm3m structure should exist, but four ionic oscillators for the PLZT polycrystalline sample were observed. This excluded the possibility that the sample could have a cubic lattice and confirmed that the tetragonal structure was present at room temperature. X-ray analysis of the PLZT sample was performed and the results were compared with infrared spectroscopy work. It was concluded that infrared optical reflectivity measurements, as a non-destructive method, can give more reliable results at the boundary cases when it is very difficult to distinguish if a material has either a cubic or tetragonal lattice structure.