Phase Transition Shift in Lead-Excess PZT Films Under UV Illumination

Abstract

Self-polarized PZT are ferroelectrics with a preferred polarization orientation at room temperature and becomes a paraelectric at high temperatures of about 460°C. The ferroelectric-paraelectric phase transition temperature depends on stoichiometry of the PZT material and therefore on preparation technology. In this work, we present an ellipsometric study of lead excess Pb_{1 + x}Zr_0.235Ti_0.765O₃ (PZT) films exhibiting a strong self-polarization in the temperature range of 20 to 500°C under UV illumination. We obtained a shift of the ferroelectric-paraelectric phase transition temperature to lower values and an increase of the optical gap E₀₃. The temperature dependences of the optical gap E₀₃, the refractive index and the absorption coefficient at fixed wavelengths were determined.

ACKNOWLEDGEMENTS

This work was supported by Grant KJB1010301 (Academy of Sciences of the Czech Republic) and 202/02/D078/A (Grant Agency of the Czech Republic), by the German Research Council (Deutsche Forschungsgemeinschaft) as part of the Research Group FOR520 and by the Herbert Quandt Foundation.