Optical and thermoluminescence properties of samarium or dysprosium doped lithium borate glass

Abstract

Borate glass is widely used in many scientific studies. By using melt-quenching technique ten samples of lithium sodium borate (LNB) doped with different concentrations of samarium oxide (Sm2O3) and dysprosium oxide (Dy2O3) were prepared. To investigate the influence of dopant on the optical and physical characteristics of the glass, X-ray Diffraction, DTA, FTIR, UV-vis-Spectroscopy and Photoluminescence analyses were performed. The amorphous nature was confirmed by X-ray diffraction technique. The physical parameters involved are density, molar volume, ion concentration, inter-nuclear distance and Polaron radius. The absorption transitions of Sm3+ starts from 6H5/2 with hypersensitive transition at 1221 nm and the Dy3+ starts from 6H15/2 with hypersensitive transition at 1256 nm. The photoluminescence emission spectra of LNB:Sm have been associated with the excitation of 544 nm, 600 nm, 613 nm, 720 nm and 747 nm, and generated at 4I7/2 → 6H5/2 (green color), 4I7/2 → 6H7/2 (orange color), 4I7/2 → 6H9/2 (orange color), 4I7/2 → 6H11/2 (red color) and 4I7/2 → 6H13/2 (red color) respectively. LNB:Dy was due to the transition of Dy3+ at 4F5/2 → 6H15/2 and 4F5/2 → 6H13/2, the photoluminescence studies showed two peaks at 479 nm (blue color) and 587 nm (green color) for all samples except the pure glass sample of lithium sodium borate. The glow curve exhibited a single peak at 164 ºC. The results show that the appropriate annealing procedure for dysprosium doped LNB is 300 °C for 30 minutes. Regarding the heating rate optimization, it was found that the appropriate heating rate of the proposed dosimeter is 6 °C. s-1. A linear dose response has been observed for photon (R2= 0.998) and electron (R2= 0.977) irradiation at 6 MV and 6 MeV, respectively. The glass dosimeter showed higher sensitivity for electron compared to photon response. The proposed TL dosimeter with concentration of 0.7 mol% of Dy2O3 has been observed to be 80 times less sensitive than TLD-100.