Thermoluminescence studies of calcium metaborate (CaB2O4) nanocrystals synthesized by solution combustion method

Abstract

This paper presents the thermoluminescence properties of calcium metaborate (CaB2O4) nanocrystals prepared by solution combustion method. The samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) and thermoluminescence (TL) analysis respectively. The XRD patterns showed the orthorhombic structure with the crystallite size at around 27 nm and the FESEM micrograph revealed the formation of nanocrystals with irregular spherical shape. Weight fraction obtained from EDX analysis consequently led to determination of an effective atomic number. It was found that the effective atomic number of CaB2O4, Zeff = 14.1 was equivalent to the effective atomic number of the bone, Zeff = 13.2 with error of 6.8 %. The samples were annealed using the TLD oven and exposed to Cobalt-60 source. TL glow curves were recorded using a Harshaw model 3500 TLD reader. The TL glow curve of this material showed a simple, single, peak located at around 150 °C. The most striking dosimetric feature of these nanocrystals was the excellence of the linearity response of a dose range from 1 Gy up to 100 Gy with R2= 0.9827 compared to the TLD-100 powder with R2= 0.9276. The high linear correlation between dose and TL response to gamma radiation suggests that calcium metaborate nanocrystals can be considered as a promising material to be used in thermoluminescence dosimetry.