UV and gamma ray induced thermoluminescence properties of cubic Gd2O3:Er3+ phosphor

Abstract

This paper reports the thermoluminescence properties of Er3+ doped gadolinium oxide nanophosphor. The phosphor is prepared by high temperature solid state reaction method. The method is suitable for large scale production. Starting materials used for sample preparation were Gd2O3, Er2O3 (0.5–2.5mol%) and fixed concentration of boric acid using as a flux. The prepared samples were characterized by X-ray diffraction technique and the particle size calculated by Scherer's formula. The surface morphology of prepared phosphor is determined by scanning electron microscopic (SEM) technique. Functional group analysis was done by Fourier transform infra-red spectroscopy (FTIR) analysis. The elemental analysis of prepared sample was determined by energy dispersive X-ray analysis (EDX) and the exact particle size of prepared phosphor for the different concentration of dopant (Er3+) was evaluated by transmission electron microscopy (TEM) technique. The prepared phosphors for different concentration of Er3+ were examined by thermoluminescence (TL) glow curve for UV and gamma irradiation. The UV 254 nm source was used for UV irradiation and Co60 source was used for gamma irradiation. The samples show well resolved broad peak covered the temperature range 50–250 °C and the peak temperature found at 126 °C for UV irradiation and higher temperature peak at 214 °C for gamma irradiation. The effect of heating rate on TL studies was presented for optimized sample. Here UV irradiated sample shows the formation of shallow trap (surface trapping) and the gamma irradiated sample shows the formation of deep trapping. The estimation of trap formation was evaluated by knowledge of trapping parameters. The trapping parameters such as activation energy, order of kinetics and frequency factor were calculated by peak shape method. Here most of the peak shows second order of kinetics. The effect of gamma and UV exposure on TL studies was also examined and it shows linear and sublinear response with dose which indicates that the sample may be useful for TL dosimetry.