A Raman and dielectric study of ferroelectric Ba(Ti1-xZrx)O3 ceramics

Dielectric and Raman scattering experiments were performed an various ceramics with composition Ba(Ti1-xZrx)O-3. Such lead-free, environmental-friendly materials were shown, from dielectric measurements, to exhibit behaviours extending from conventional to relaxer ferroelectrics on increasing the zirconium concentration. The evolution of the: Raman spectra was studied as a function of temperature for various compositions, and the spectroscopic signature of the corresponding phases was determined. In the relaxer state, the variation of the integrated intensity of the Raman lines with temperature showed a plateau at low temperature. This anomaly was also detected as a peak in depolarization current measurements, and attributed to ergodicity breaking which characterizes usual relaxer systems. Raman results hint at locally rhombohedral polar nanoregions resulting from the random fields associated with Zr ions.