Trap characteristics of UV-activated Y3(Al,Ga)5O12:Ce3+phosphorsA

Abstract

tThis paper reports on the trap characteristics of commercially obtained Y3(Al,Ga)5O12:Ce3+phosphorpowder. The effects of UV irradiation time and different heating rates have been discussed using differentthermoluminescence (TL) techniques. In the TL glow curves of the Y3(Al,Ga)5O12:Ce3+phosphor measuredin the temperature range between room temperature (RT) and 250◦C, two TL peaks were observed, amaximum centered around 74◦C and a shoulder at around 163◦C when excited with UV radiation. Varyingthe UV irradiation (exposure) time or hence absorbed dose and heating rate significantly affected the peakintensity (Im) and peak temperature (Tm) of the glow curve. The UV exposure time was varied from 3 minto 20 min and we noted that the TL intensity increased with UV exposure time in the range 3–15 min. Thismay be explained on the basis of second order recombination kinetics taking place due to a re-trappingprocess of the excitation. The intensity of the two TL peaks moved to the higher temperature side withan increase in the heating rate. The kinetic parameters at various heating rates namely activation energy(E), order of kinetics (b) and frequency factor (s) of the Y3(Al,Ga)5O12:Ce3+sample were determined bythe variable heating rate method, peak shape method and TL Anal Glow Curve Deconvolution (GCD)techniques.