Photoluminescence, thermoluminescence and EPR studies on Zn₄B₆O₁₃

Abstract

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.