We have been working on the Lu₂O₃:Ln,M (Ln= Pr/Tb, M= Ca, Sr, Ba, Ti, Hf, Nb, Ta) storage and persistent phosphors for more than ten years now. More recently we have discovered that also LuPO₄:Eu shows ability to store energy when exposed to ionizing radiation. All the compositions share some characteristics. For example, they need high-temperature treatment to efficiently store energy and they do not degrade after over-exposure to ionizing radiation. What else all these compositions have in common is developing a broad absorption in UV-Vis part of spectrum during energy storage. These bands intensities mirror the dose of high-energy radiation they are exposed to. Figure 1 presents absorption spectra of Lu₂O₃:Tb,Hf (left) and LuPO₄:Eu (right) storage phosphors before and after their exposure to X-rays. Despite some differences, in both cases ionizing radiation induced a broad absorption band extending in NUV-Vis (Lu₂O₃) or whole Vis (LuPO₄) part of spectrum. In our presentation we shall analyze the origin of the new absorption bands in both compositions and will relate them to the energy storage mechanisms. We will also analyze their usability for optically stimulated luminescence or radiophotoluminescence generation in the materials.

The authors gratefully acknowledge financial support by the Polish National Science Centre (NCN) under the grant #UMO-2014/13/B/ST5/01535.