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

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 Pb1 + xZr0.235Ti0.765O3 (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.