Effects of doping concentration on thermoluminescence parameters of CaAl2O4:Re3+ (Re3+ = Dy3+, Sm3+, Tm3+) prepared by combustion method

Highlights: • Undoped and five concentration of CaAl₂O₄:Re³⁺ (Re = Dy³⁺, Sm³⁺, Tm³⁺) was synthesized by combustion method. • Characterized using XRD, SEM, and FTIR. • Investigate their optimum concentration, the effect of different rare earth elements. • Kinetic parameters of the traps were calculated by CGCD methods. In this study, we investigate thermoluminescence (TL) of calcium aluminate undoped and doped with three rare earth elements at five different concentrations, synthesized by the combustion method, which can be designed for relevant applications with suitable doping of activators. From the XRD data, we determine the phase, structure and particle size, using Scherrer's equation. Investigations on the morphology and functional groups of the prepared samples are carried out by using the techniques of field emission scanning electron microscope (FE-SEM) and Fourier transform infrared (FTIR) spectroscopy. The samples are exposed to γ-ray doses of 10 Gy to investigate their optimum concentrations, the effects of doping with different rare earth elements and kinetic parameters. The TL glow curves are deconvoluted using the TLanal program, and TL trapping parameters, viz. activation energy (E), frequency factor (s) and order of kinetics (b) of trapped charges, are obtained. We theoretically evaluate lifetimes (τ) of the charges in the traps present in these phosphors using kinetic parameters. The phosphor CaAl₂O₄:Sm³⁺ has the most intense stable TL peaks and the trap charge-lifetime in the range of years, which make it an eligible candidate for dosimetric applications. We also observe photoluminescence spectra of doped calcium aluminate at the optimum concentration exhibiting maximum TL intensity.