Synthesis of BaSO4 doped with rare earth ions and characterization of its luminescent response

Abstract

In this work the luminescent properties of BaSO4 phosphor (doped with Eu, Tm, Dy, Ce and Pr), synthesized by the solid state combustion technique, were analyzed. Studies of the emission spectrum of BaSO4 pellets doped with rare earths ions, as well as the TL and OSL response for gamma radiation, X-rays and beta radiation were performed. TL readings were performed using Harshaw 3500 reader with a heating rate of 2°C/s. For OSL response we used the Lexsyg Smart OSL reader equipped with excitation LEDs in the blue and infrared region. The results showed that the highest sensitivity in the TL response was obtained with Eu dopant concentration of 0.02 mol%. This concentration was used to prepare BaSO4 pellets doped with Eu, Tm and Dy and to characterize their luminescent response. The results showed that the pellets prepared with Eu have a TL response that is around 20 times greater than that obtained with the Dy and Tm dopants. On the other hand, the OSL response of the pellets, stimulated by blue light (BSL), were practically similar. The pellets prepared with Ce and Pr did not show BSL response and the pellet with all dopants did not show any response after infrared excitation. The study of the TL glow curve obtained after the BSL reading i.e., the residual TL, showed that for BaSO4:Eu pellets the peak remained the same, indicating that the recombination centers for OSL are not the same for TL. While whereas for the BaSO4:Tm and BaSO4:Dy pellets, the TL peak around 100°C decreased after the BSL reading and there was an increase in the peak area at high temperature. This fact suggests that the phototransference phenomenon may be occurring in this case. The calibration curve of BaSO4:Eu irradiated with gamma radiation beam from the 137Cs showed a linear response and the minimum detection limit is 17.9 μGy, while this limit is 0.59mGy for the BSL response. These results show that the TL sensitivity is greater than the BSL. The results obtained show the potential for the use of this phosphor for the dosimetry of ionizing radiation.