Thermoluminescence from Cu Doped Lithium Tetraborate Irradiated with X-ray and γ Using ¹³⁷Cs Radioactive Source

Abstract

Lithium tetraborate (Li2B4O7) pellets prepared by using water/solution assisted method were synthesized and characterized. Copper was used as doping material in order to enhance the Li2B4O7 thermoluminescent properties. For synthesis heating temperature parameters were defined at 750 °C for 2 hr, followed by 150 °C for another 2 hr. The materials were produced at five different Cu concentrations: 0.02, 0.04, 0.06, 0.08, and 0.1 wt%. The luminescent and morphological characterizations were performed by X-ray diffraction (XRD), Scanning electron microscope (SEM), Photoluminescence (PL), and Ultraviolet-visible spectroscopy (UV-Vis). XRD and SEM analysis of intrinsic and doped materials confirmed the obtained Li2B4O7 structure and show its morphology. XRD patterns of the Li2B4O7 matched a tetragonal crystal structure. Crystals of Li2B4O7 of an average size of 50 nm were obtained. The presence of the copper dopant was confirmed in crystals of Li2B4O7:Cu by SEM-EDS (energy dispersive spectroscopy X-ray). The emission spectrum of Cu doped Li2B4O7 showed a prominent peak at 367 nm, while the main UV-Vis absorption was observed from 240 nm to 300 nm due to Cu+ ion 3d10 → 3d9 4s transitions. The thermoluminescent (TL) response was studied for both γ radiation and X-ray. A 661.7 keV γ radiation using a 137Cs source at doses of 50, 100, 200, 300, 400 and 500 mGy was applied to Li2B4O7:Cu (0.1 wt%) pellets. An X-ray source was used at doses of 600, 800 and 1000 mGy to irradiate pellets of Li2B4O7:Cu (0.02, 0.04, 0.06, 0.08 and 0.1 wt%). A linear TL response was observed for both X-ray and γ radiation. The kinetic parameters were calculated using the peak shape method for the Li2B4O7:Cu (0.1 wt%).

Synthesis and characterisation of LiB 3 O 5 nanophosphor as a TL dosimeter

“…To choose a suitable activator for LiB 3 O 5 , the synthesised sample was doped with different concentrations (0.1, 0.2, 0.3, 0.4, 0.5, 1, 2, 3, and 4 wt %) of various dopants such as Al, Cu, Mn, Mg and PVP. These dopants were selected based on the previous studies on lithium tetraborate [6][7][8][9][10][11][12] and lithium triborate [14][15][16][17][18]. The doped nanophosphors were sintered at 710°C for 4 h and their response to irradiation was investigated.…”

“…In particular, lithium borates with an effective atomic number similar to the biological tissue are appropriate materials for radiation dosimetry purposes [4,5]. Most of the studies on TL properties of lithium borates are performed on lithium tetraborate (bulk or nanosized) with various activators [6][7][8][9][10][11][12]. These studies have shown that TL properties of lithium tetraborate depend on the synthesis method, type, and concentration of dopants.…”

“…Unfortunately, Li 2 B 4 O 7 : Mn (TLD-800) phosphor, the first TL material commercialised, showed several drawbacks such as poor TL intensity, limited dose linearity, fading and energy dependence. For these reasons, Li 2 B 4 O 7 was doped with other activators such as Cu, In; Cu, In, Ag; Mg, Cu, P [8][9][10][11][12]. Among them Li 2 B 4 O 7 :Cu, Ag, P showed some improvement.…”