ORDER-DISORDER AND STRUCTURAL PHASE-TRANSITIONS IN SOLID-STATE MATERIALS BY RAMAN-SCATTERING ANALYSIS

The temperature dependence of the vibrational wavenumbers, of the anha rmonic and/or order-disorder origin of the damping and of the Raman in tensities are briefly presented. On that basis, it is then shown that one can obtain information such as the height of the potential barrier , the orientational correlation time, the spatial correlation length a nd the anharmonic contribution to the Raman peak evolution with temper ature. The concepts were applied and exploited with success in three c haracteristic cases, diethylenetriammonium chlorocadmate [(denH(3))CdC l5] single crystals, zinc thiourea sulphate [ZTS] single crystals and lead-lanthanum zirconate-titanate [PLZT] ceramics in which order-disor der and structural phase transitions are observed. (C) 1997 John Wiley & Sons, Ltd.