EPR identification of defects responsible for thermoluminescence in Cu-doped lithium tetraborate (Li2B4O7) crystals

► We use EPR to identify a Cu2+ center and two Cu0 defects in Cu-doped Li2B4O7. ► These defects form when our crystal is irradiated with X-rays at room temperature. ► We also observe two above-room-temperature thermoluminescence (TL) peaks. ► A pulsed anneal experiment correlates the decay of the EPR signals to two TL peaks. ► We identify the mechanism and participants responsible for the TL peaks.