[en] Orthophosphate-based phosphors have been used widely as efficient materials for the luminescence applications. Thermoluminescence (TL) properties of luminescent materials help us to find the suitability of the phosphors for the TL dosimetric application. In this work, a series of Dy${}^{3+}$ doped and Mn${}^{2+}$-codoped sodium yttrium phosphate Na${}_3$Y(PO${}_4$)${}_2$ phosphors were synthesized via a solid-state reaction method and thermoluminescence behavior were studied. To observe the effect of the dopant and codopants on phase purity and crystalline structure of phosphors, X-ray diffraction method analyses were carried. In addition, the morphological images were examined; chemical composition and functional groups were confirmed. Herein, the Dy${}^{3+}$-doped and Mn${}^{2+}$-codoped Na${}_3$Y(PO${}_4$)${}_2$ phosphors were irradiated by 1 kGy-dose γ-radiation and Na${}_3$Y(PO${}_4$)${}_2$:0.07Dy${}^{3+}$ showed a intense TL intensity peak at 178 °C, whereas Mn${}^{2+}$-Na${}_3$Y(PO${}_4$)${}_2$:0.07Dy${}^{3+}$, 0.07Mn${}^{2+}$ phosphors showed at 134 °C. The effect of codopant Mn${}^{2+}$ on the TL properties of Dy${}^{3+}$-doped Na${}_3$Y(PO${}_4$)${}_2$ phosphors and irradiation dose were investigated. The optimized Na${}_3$Y(PO${}_4$)${}_2$:0.07Dy${}^{3+}$ phosphor was showed a linear response to irradiation as a function of dose in the range of the 50 Gy–1.5 kGy. The glow curves were deconvolated and the TL kinetic parameters of phosphors were obtained by adopting various methods, revealing that the glow curves exhibited the second-order kinetics, and activation energies were calculated. The kinetic parameters of prepared samples were compared with the other TL materials. The obtained results confirm that the phosphors may have potential applications as TL dosimetry materials to measure low irradiation.

[en] Al${}_{20}$Te${}_{75}$X${}_5$ (X = Si, Ge, As, Sb) glasses prepared by the melt quenching method exhibit threshold switching. Local structure of these glasses studied by ${}^{27}$Al MAS-NMR measurements reveals that Al is in four-, five- and sixfold coordination. For Al to be in higher coordination states, Te transfers its lone pair electrons. Due to the higher coordinated Al and Te, the cross-linking in the network increases. The increased cross-linking and rigidity constraint the structural reorganization required for memory switching, resulting in the observed threshold switching. Interestingly, glass transition and crystallization temperatures were found to be high for Al${}_{20}$Te${}_{75}$Si${}_5$ glass and low for Al${}_{20}$Te${}_{75}$Sb${}_5$ glass. Also, the bond energy of Si–Te is higher than the bond energy of Sb–Te. Correspondingly, the threshold voltage is high for Al${}_{20}$Te${}_{75}$Si${}_5$ glass and low for Al${}_{20}$Te${}_{75}$Sb${}_5$ glass. The ${}^{[6]}$Al site peak shows a split which may offer greater insight into the structure of these glasses.

[en] Influence of volatile fluxes like NH₄Cl, B(OH)₃ and their combination on the photo luminescence and morphological properties of ZrO₂:Eu³⁺ phosphor was investigated. The samples were characterized by XRD, UV–visible spectroscopy, scanning electron microscopy and photoluminescence spectra. XRD pattern shows that the samples prepared using ammonium chloride and by combination of ammonium chloride, boric acid crystallizes in tetragonal phase, whereas samples prepared without flux and using boric acid, crystallizes in cubic phase. The results revealed that particle size, morphology, phase and photoluminescence emission color were largely influenced by the flux. Type of flux employed significantly influenced the morphology and emission color of the phosphor. Addition of two fluxes resulted in pure white-light emission, with CIE chromaticity coordinates of (0.327, 0.331), which is very close to the essential requirement to the NTSC (National Television System Committee) system for standard white light.