Low‐temperature order–disorder phase transition of PLZT x: 95:5 ceramics, with La Content x = 0.5–4% by weight, determined by Raman spectroscopy

Investigations of the Raman spectra of lead–lanthanum–zirconate‐titanates (PLZT) x:95:5 (x = 0.5, 1, 2, 3 and 4 wt.% La2O3) ceramics over a range of temperature from 10 K to room temperature are presented. With increasing temperature the intensity of the Raman spectra, corrected for the Bose population factor, is lower above the transition temperature T0 = 130 K; this intensity lowering is characteristic of disorder‐induced spectra. This temperature dependence is interpreted by means of the theory of fluctuating clusters in the low‐temperature phase and the order parameter below T0 was determined. Associated with this phase transition, it was found that some softening effects are present in the vibrational wavenumbers.