Caracterização estrutural óptica e dosimétrica de CaSO4:Tb, CaSO4:Mn e CaSO4:Mn,Tb produzidos por rota de evaporação lenta

Abstract

The objective of this work was to investigate the luminescence properties of CaSO4:Tb, CaSO4:Mn e CaSO4:Mn,Tb synthesized by slow evaporation route. The crystalline structure, morphology, thermal and optical properties of the phosphors were characterized by X-ray diffraction analysis (XRD), Scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Raman spectroscopy, infrared spectroscopy, photoluminescence (PL) and radioluminescence (RL). Moreover, using thermoluminescence (TL) and optically stimulated luminescence (OSL) techniques, the dosimetric properties of the phosphors, such as emission spectra, reproducibility, linearity, fading of the luminescent signal, OSL decay curves, correlation between TL and OSL emissions and lowest detectable dose (LDD) were comprehensively investigated. For dosimetric analyses the samples were irradiated with doses of between 169 mGy and 10 Gy. TL emission spectra, PL and RL confirmed the presence of Tb3+ and Mn2+ ions in crystalline matrices. In the OSL analyses, the samples showed a typical exponential OSL decay curve with the predominance of a fast decay component, indicating that the charge carrier trapping centers have a high photoionization cross-section for blue LEDs, and a LID on the order of mGy. The luminescent signals showed to be linear and reproducible in the studied dose range. The high TL sensitivity of phosphors was proven when comparing with commercially available dosimeters. It was also observed that co-doping with Mn2+ and Tb3+ contributed to a reduction in fading compared to that observed in the emissions of CaSO4:Mn and CaSO4:Tb.