Light-induced structural changes in Eu-doped (Pb,La)(Zr,Ti)O3 ceramics

Fluorescence spectra of poled and unpoled Eu-doped (Pb,La)(Zr,Ti)O3 ceramics with various compositions were measured using 580 nm excitation. The ratio of the intensities of the Eu3+5D0→7F2/5D0→7F1 fluorescence transitions was used as an indicator for the symmetry of the Eu3+ site. As the symmetry decreases, the ratio increases. Increasing the Zr content in (Pb,La)(Zr,Ti)O3 increases the ratio, indicating that the symmetry of the Eu3+ site decreases. Exposure of the Eu-doped (Pb,La)(Zr,Ti)O3 samples to UV light also increases the intensity ratio, indicating that UV light exposure leads to structural distortions in Eu-doped (Pb,La)(Zr,Ti)O3 samples, lowering the Eu3+ site symmetry.