Synthesis, thermoluminescence and dosimetric properties of La-doped zinc borates

Abstract

Dependence on the dose of beta radiation of undoped and La-doped ZnB2O4 powder samples at 1%, 2%, 3%, 4%, 5% and 10% (by weight) was investigated by thermoluminescence technique. Powder samples were synthesized by the nitric acid method using the starting oxides [zinc oxide (ZnO), boric acid (H3BO3) and doped element oxide (La2O3)]. The samples were characterized by X-ray diffraction (XRD). The thermoluminescence (TL) properties of the powder samples were measured with Risø TL/OSL DA-20 reader. TL glow curves were obtained with heating at a constant heating rate of 5°C/s up to 450°C. The dose response curves of the powder samples exposed to 90Sr beta radiation (40mCi) were obtained in the dose range from 143mGy to 60Gy. Dose responses and minimum detectable dose (MDD) values for increasing radiation doses of the powder samples were determined. The dose responses of all the samples have shown a quite linear response to beta radiation. MDD value of 10% La-doped ZnB2O4 powder sample which shows a high temperature peak at 207°C was determined as 4mGy. MDD values for 1%, 2%, 3%, 4% and 5% La-doped ZnB2O4 powder samples were also determined as 10mGy, 50mGy, 10mGy, 10mGy and 30mGy, respectively. Luminescence intensities of the powder samples were shown to be likely to be used for low radiation doses.