RADIATION EFFECT ON THE LUMINESCENCE OF LIYF4-ER3+

Luminescence and also the effects of ionising radiation on luminescenc e have been investigated in LiYF4:Er. The defects created by ionising radiation are studied by means of Thermally Stimulated Luminescence (T SL) and Electron Spin Resonance (ESR). TSL studies indicate a prominen t glow peak at 386-412 K, whose position is found to depend on the rad iation dose. Two defect centres, tentatively assigned to F-centres, ar e observed at room temperature. Step annealing measurements suggest a connection between these centres and the TSL glow peak. Photoluminesce nce studies indicate considerable reduction in emission intensity whic h appears to arise from the distortion of the lattice around the Er3ion caused by the defect centres. An explanation of the observations i s suggested on the basis of impurity ion-defect centre formation. (C) 1998 Elsevier Science B.V.