Change of photoluminescence property of ferroelectric compounds with the gamma-ray irradiation

We investigated the emission properties of Bi3.25La0.75Ti3O12 polycrystals and (K0.5Na0.5)(Mn0.005Nb0.995)O3 thin films with strong gamma (γ)-ray irradiation by using temperature dependent photoluminescence spectroscopy. At the lowest temperatures, sizable visible emissions were identified for the γ-ray irradiated samples as well as un-irradiated ones. In both kinds of compounds, the visible emission intensity tended to be increased without changing the spectral shape, as the γ-ray dose increased. This indicates that the γ-ray irradiation should increase all kinds of already-existing defects evenly, without preferring the formation of some particular type of defect.