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

Abstract

Nanophosphors of barium strontium sulfate complex (Ba1-xSrxSO4)99.8%:Eu0.2% (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 (Ba1-xSrxSO4)99.8%:Eu0.2% exhibit an orthorhombic structure with semispherical particle shape. The lattice parameters of (Ba1-xSrxSO4)99.8%:Eu0.2% 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 (Ba1-xSrxSO4)99.8%:Eu0.2% series were recorded and compared. The substitution of Ba2+ by Sr2+ cations shift the trap centers in the host of (Ba1-xSrxSO4)99.8%:Eu0.2% 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 Tstop experimental method, and the computerized glow curve deconvolution (CGCD) program. Tm–Tstop experiment indicates that there are three trapping levels in both (BaSO4)99.8%:Eu0.2% and (SrSO4)99.8%:Eu0.2% 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 (Ba0.88Sr0.12SO4)99.8%:Eu0.2%. These values are used as input for CGCD. The figure of merit (FOM) during fitting procedures is determined.