PHOTOLUMINESCENCE, THERMOLUMINESCENCE AND EPR STUDIES ON ZN4B6O13

Photoluminescence, thermoluminescence and temperature dependent EPR measurements on Zn4B6O13 are reported and discussed. The photoluminescence properties show that the intrinsic violet emission of this compound may originate from a strongly localised self-trapped exciton state. Four types of UV-induced paramagnetic centres are identified on the basis of g-values and hyperfine splitting, namely electrons trapped in two types of oxygen vacancies, electrons trapped on or near Mn2+ impurities and holes trapped by borate groups. The thermal decay of the paramagnetic centres is discussed in relation to the thermoluminescence.