Effect of strontium additive on thermoluminescence properties of (Ba1-xSrxSO4)99.8%: Eu0.2% nanophosphor

Nanophosphors of barium strontium sulfate complex (Ba_1-xSr_xSO₄)_99.8%:Eu_0.2% (0 ≤ x ≤ 1) were prepared through the chemical co-precipitation method at room temperature. Precipitated samples were characterized using X-ray diffraction (XRD), dynamic light scattering (DLS) and high resolution transmission electron microscope (HRTEM) techniques. The obtained XRD patterns from the prepared nanophosphate series (Ba_1-xSr_xSO₄)_99.8%:Eu_0.2% exhibit an orthorhombic structure with semispherical particle shape. The lattice parameters of (Ba_1-xSr_xSO₄)_99.8%:Eu_0.2% solid crystals change and the cell volume decreases with the increase of x value of strontium. The thermoluminescence (TL) glow curves induced by gamma rays of (Ba_1-xSr_xSO₄)_99.8%:Eu_0.2% series were recorded and compared. The substitution of Ba²⁺ by Sr²⁺ cations shift the trap centers in the host of (Ba_1-xSr_xSO₄)_99.8%:Eu_0.2% material to the higher temperature side. The TL glow curve (GC) of sample with x = 0.12, with grain size ranging between 13–31 nm, reveals that it has deep trap centers, and higher TL sensitivity. The different heating rates effect of the glow peaks of samples with x = 0, 0.12 and 1 showed that they follow the first-order kinetics. These samples have been studied and analyzed with the help of both T_stop experimental method, and the computerized glow curve deconvolution (CGCD) program. T_m–T_stop experiment indicates that there are three trapping levels in both (BaSO₄)_99.8%:Eu_0.2% and (SrSO₄)_99.8%:Eu_0.2% sulfate samples at 452, 489, 543 K and 487, 513, 530 K respectively, while five peaks at 458, 486, 499, 544 and 556 K in the complex GC of (Ba_0.88Sr_0.12SO₄)_99.8%:Eu_0.2%. These values are used as input for CGCD. The figure of merit (FOM) during fitting procedures is determined.