Unlocking the effect of Li and Ce ions on the thermoluminescence and optically stimulated luminescence signals of the MgB4O7 compound

Abstract

Magnesium tetraborate (MgB₄O₇) is an example of a material that has attracted the attention of researchers in the field of ionising radiation dosimetry. Several challenges are present in order to achieve considerable advances in luminescence dosimetry. The incorporation of efficient dopants in the host matrix has been an experimentally useful but limited strategy. The lack of specific information about the introduced defects as well as their connection with the trapping and recombination processes associated with light emission may be quoted as challenging examples. Here, we demonstrate the influence of lithium incorporation on Optically Stimulated Luminescence (OSL)/Thermoluminescence (TL) signal modification/suppression of MgB₄O₇ by combining experimental and computational procedures. Li substitution into the Mg site leads to a signal suppression due to the probable quenching of the F_s and F_s⁺ centres in MgO and the formation of O′′_i, drastically reducing the possibility of MgO anti-Schottky defect formation in MgB₄O₇. When using Li-co-doped MgB₄O₇:Ce³⁺, the Li ions act as a charge balancer, facilitating the entry of Ce ions into the interstitial pores and making possible a positive synergistic effect on the luminescence and dosimetric properties. These findings provide new insights into designing more efficient dosimeters by tuning dopants.