High-pressure Raman investigation of the Pb-free relaxor BaTi_0.65Zr_0.35O₃

We report high-pressure Raman measurements (up to 27 GPa) on the perovskite-type relaxor ferroelectric BaTi_0.65Zr_0.35O₃(BTZ₃₅). Distinct changes of the Raman spectra with increasing pressure illustrate that BTZ₃₅ presents important pressure instabilities leading to at least two phase transitions around 5.7 GPa and 15.1 GPa, respectively. The observed pressure-induced spectral changes for BTZ₃₅ are reminiscent of features that have been observed for pure BaTiO₃, thus for a classic ferroelectric. The latter is surprising since earlier reports indicate a relaxor-characteristic Raman signature as a function of temperature, thus illustrating that BTZ₃₅ might well occupy a peculiar niche in perovskite-type ferroelectrics.