Investigation of structural, photoluminescence, and thermoluminescence properties of Praseodymium doped CaWO4 phosphor

The structural, optical, photoluminescence and thermoluminescence behaviors of Praseodymium doped CaWO4 (Ca1-xPr2x/3WO4; x = 0.01, 0.02, 0.03, 0.04, 0.05) phosphors prepared via conventional solid-state reaction route were reported in this paper. X-ray diffraction study revealed the fact that all the synthesized samples crystallize in a tetragonal structure with I41/a (88) space group and the structural parameters were obtained from the Reitveld refinement. The unit cell volume was found to rise with the increase in Pr concentration. The bandgaps of the prepared samples were obtained from the UV-Visible absorbance spectra by using the Wood-Tauc method. Bandgap and unit cell volume of the prepared samples were directly proportional to each other. Photoluminescence behaviors were investigated from the excitation and the emission spectra. The PL spectra highlight that the quenching occurs at x = 0.02 and the critical distance for energy transfer of the phosphor was found to be 20 angstrom. Dexter theory was applied to determine the mechanism of quenching and confirmed that the concentration quenching was caused by the dipole-dipole interaction. CIE Chromaticity denoted that the phosphors emit red color. Color purity and CCT of the material were calculated. Thermoluminescence behaviors were studied with different durations of UV dose for the composition x = 0.02 and the kinetic parameters were calculated. Variations of TL emission intensity with temperature confirmed the second-order kinetics of the phosphor with a critical quenching concentration at x = 0.02.