Demystification of luminescence properties and the near imperceptible thermal quenching of Sm3+-doped tungstate phosphors.

Ultra-high thermally stable Ca2MgWO6:xSm3+ (x = 0.5, 0.75, 1, 1.25, and 1.5 mol%) double perovskite phosphors were synthesized through solid-state reaction method. Product formation was confirmed by comparing the X-ray diffraction (XRD) patterns of the phosphors with the standard reference file. The structural, morphological, thermal, and optical properties of the prepared phosphor were examined in detail using XRD, Fourier transform infrared spectra, scanning electron microscopy, diffused reflectance spectra, thermogravimetric analysis (TGA), photoluminescence emission, and temperature-dependent PLE (TDPL). It was seen that the phosphor exhibited emission in the reddish region for the near-ultraviolet excitation with moderate Colour Rendering Index values and high colour purity. The optimized phosphor (x = 1.25 mol%) was found to possess a direct optical band gap of 3.31 eV. TGA studies showed the astonishing thermal stability of the optimized phosphor. Additionally, near-zero thermal quenching was seen in TDPL due to elevated phonon-assisted radiative transition. Furthermore, the anti-Stokes and Stokes emission peaks were found to be sensitive toward the temperature change and followed a Boltzmann-type distribution. All these marked properties will make the prepared phosphors a suitable candidate for multifield applications and a fascinating material for further development.

Thermoluminescence properties of copper-doped TiO2 nanoparticles synthesised using co-precipitation method for high-dose gamma dosimetry.

In this work, copper (Cu)-doped titanium dioxide (TiO2) nanoparticles were prepared by co-precipitation. For studying the morphological properties, the copper doped titanium dioxide (TiO2:Cu) nanocrystalline structures were characterised through powder X-ray diffraction and field emission scanning electron microscopy. The prepared TiO2:Cu nanoparticles were annealed at two temperatures, namely, copper doped titanium dioxide annealed at 723 K temperayure (TC1) and copper doped titanium dioxide annealed at 1073 K temperayure (TC2). The annealed samples were exposed to gamma radiation of 10-Gy-to-25-kGy doses. Thermoluminescence and dosimetric properties were evaluated using a thermoluminescent dosemeter reader. The glow curves of the TiO2:Cu nanoparticles were analysed. The thermoluminescence (TL) response of samples exhibited good linearity between 100 Gy and 10 kGy with high sensitivity of 1755.25 (TC1) and 5587.06 (TC2) counts g-1Gy-1 and a minimum detectable dose of 2.9666 Gy (TC1) and 0.4892 Gy (TC2). The fading of signals was observed by 12% for TC1 and 10% for TC2 samples after a week of storage.