Radiation effect on the luminescence of LiYF 4:Er 3+

Abstract

Luminescence and also the effects of ionising radiation on luminescence have been investigated in LiYF 4:Er. The defects created by ionising radiation are studied by means of Thermally Stimulated Luminescence (TSL) and Electron Spin Resonance (ESR). TSL studies indicate a prominent glow peak at 386–412 K, whose position is found to depend on the radiation dose. Two defect centres, tentatively assigned to F-centres, are observed at room temperature. Step annealing measurements suggest a connection between these centres and the TSL glow peak. Photoluminescence studies indicate considerable reduction in emission intensity which appears to arise from the distortion of the lattice around the Er 3+ ion caused by the defect centres. An explanation of the observations is suggested on the basis of impurity ion-defect centre formation.