Thermally stimulated and recombination processes in MgB4O7 investigated by systematic lanthanide doping

In this work a systematic study of the thermoluminescence (TL) of lanthanide-doped MgB4O7 was carried out to elucidate the thermally stimulated and recombination processes in this material. MgB4O7 samples undoped or doped with lanthanides (Ln) were synthesized using solution combustion synthesis. Li, Na and K were investigated as co-dopants to increase the Ln luminescence. The crystalline structure of the samples was confirmed using X-ray diffraction and the TL spectra were measured. The data shows that Ce3+ and possibly Mn2+ are typically associated with TL peaks at ~250 °C and ~300 °C, whereas Sm3+, Gd3+, Tb3+, Dy3+ and Tm3+ are associated with TL peaks at ~190 °C and ~340 °C (temperatures are approximate and refer to a heating rate of 5 °C/s). The patterns that emerge suggest different trapping mechanisms: electron traps being associated with the 250 °C and 300 °C and hole traps being associated with the ~190 °C and ~340 °C TL peaks. The roles of Pr, Nd, Eu, Ho, Er and Yb in the TL process cannot be ascertained. This work indicates that a systematic study of Ln-doped samples can lead to an improved understanding of the thermally stimulated and recombination processes in a material, which is extremely valuable in developing a guided approach towards the development of new luminescent materials.