Raman spectroscopy and effective dielectric function in PLZT<i>x/</i>40<i>/</i>60

Abstract

The Raman spectra of the ceramics PLZT x/40/60 have been measured in the temperature range 20‐800 K. An assignment of the Raman modes is presented using the results of the effective medium approximation for the IR data. Factor-group analysis is presented for the case of off-site position of cations or unit cell doubling, which allows a higher number of active phonons in the IR and Raman spectra. The presence of Raman-active modes in the cubic phase is associated with local unit cell doubling and symmetry breakdown due to the off-site cations. (Some figures in this article are in colour only in the electronic version)