This work presents a fresh insight into the excited charges trapping in the Lu₂O₃:Tb,M (M= Ti, Hf) ceramics and their characteristics as storage and/or persistent luminescence phosphors. The results were obtained by applying an exceedingly versatile set of experiments based on thermoluminescence and thermoluminescence excitation spectroscopy and exposed a dual-nature of these materials. In the contrary to the previous research, here we found that at least some of these materials can generate efficient persistent luminescence due to the presence of shallow traps which can be charged only upon specific irradiation conditions – by the spin-forbidden 4f→5d transition of Tb³⁺ around 360 nm and, possibly, the ⁷F₆→⁵D₃ intra-configurational transition of the activator at just slightly longer wavelengths. Besides that, changing the sample charging temperature the efficiency of filling the traps – both deep and shallow – with the 360 nm radiation varied greatly and exposed a very broad distribution of trap energies. Charging with 360 nm radiation at room temperature fills only the shallow traps giving, never reported in Lu₂O₃:Tb,Ti and Lu₂O₃:Tb,Hf, intense persistent luminescence, while at higher temperatures the deep traps are filled. At any temperature, radiation of wavelengths < 320 nm fills almost exclusively deep traps responsible for TL at high temperatures, 230 °C in Lu₂O₃:Tb,Hf and 355 °C in Lu₂O₃:Tb,Ti.

Thermoluminescent properties and energy storage characteristics of Lu₂O₃:Tb,M (M = Hf, Ti, Nb) sintered ceramics induced by ionizing radiation are presented and discussed. Dose-response dependence, radiation hardness and fading are studied. A linearity of the former exceeding seven orders of magnitude is confirmed for Lu₂O₃:Tb,Hf and Lu₂O₃:Tb,Nb ceramics. Lu₂O₃:Tb,Hf shows the best TL performance and also its fading is the lowest reaching 15% over 7 h and shows tendency to saturate. During the same period of time the Lu₂O₃:Tb,Ti, despite having TL at higher temperatures, losses about 25% of the stored energy and the TL signal of Lu₂O₃:Tb,Nb fades by almost 40% over 7 h. First order TL kinetics is confirmed for all three compositions. A self-dose effect in Lu₂O₃:Tb,Hf due to a natural content of the radioactive isotope (2.6%) is proved to be important for long-time reading of low doses.