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The structural and luminescent properties of TiO 2 and TiO 2 :Sm 3+ powder, synthesized by microwave irradiation using benzyl alcohol as solvent, were studied over an annealing range of 200–1000 °C. Structural and luminescent characterization was carried out by XRD, TEM, HRTEM, HRSEM and PL. Pure synthesized TiO 2 presents similar structural characteristics to other methods and its transformation from the anatase to the rutile phase occurs between 600 and 800 °C. It was determined that the anatase phase of TiO 2 is stabilized when doped with Sm 3+ , even at temperatures up to 1000 °C. Crystal growth of TiO 2 :Sm 3+ powder is very slow, measuring 5 nm at 200 °C and 29 nm at 800 °C. It was observed that the particles consist of nano-sized crystals for all working conditions. Microwave irradiation technic allowed the successful incorporation of Sm 3+ ions into the TiO 2 host lattice, so it is reasonable to conclude that Sm 3+ ions distorted octahedron of TiO 6 to replace Ti 4+ ions. TiO 2 :Sm 3+ nanocrystals show emission of Sm 3+ ion in the visible wavelength region. The visible photoluminescence correspond to transitions from the excited 4G 5/2 level to the 6H 11/2 , 9/2 , 7/2 , 5/2 levels, respectively. The results of spectroscopic measurements of luminescence excitation, imply that Sm 3+ emissions, are due to indirect excitation of the Sm 3+ ions through an energy transference process from electron-hole pairs generated in the TiO 2 host. The increased emission intensity is directly related with high crystallinity obtained by annealing treatment. [ABSTRACT FROM AUTHOR]

In the present work, terbium-doped yttrium hydroxide was successfully synthesized by the microwave-assisted hydrothermal method using yttrium nitrate, terbium chloride, and lithium hydroxide as precursors; the study is based on samples with different terbium concentrations. X-ray diffraction indicates a pure hexagonal structure corresponding with the Y(OH)3 structure, as well as a preferential growth along (110) planes for the Tb-doped samples. FTIR confirms the presence of Y–OH bonds and no adsorbed nitrogen or N–O bonds. SEM images indicate the formation of rods smaller than 1 μm in length and diameters ranging from 80 to 55 nm while TEM images confirm the presence of large areas corresponding to (110) planes. The sample doped at 4 at.% presented the maximum photoluminescent intensity, though the sample doped at 2 at.% presented the highest values of quantum yield (23.5%). Quantum yield values decay with terbium concentration to a value of 7.89% for the 10 at.% concentration, such changes are attributed to a quenching effect and to differences in the photon-extraction efficiency. Photoluminescence decay time values decrease monotonically from 1.133 for the 2 at.% sample to 0.453 ms for the sample doped at 10 at.%, such behavior is attributed to a self-stimulated emission. [ABSTRACT FROM AUTHOR]

In this work, both undoped and Thulium (Tm3+) doped (0.3–10 mol%) magnesium pyrophosphate (Mg 2 P 2 O 7) powders were synthesized by the solvent evaporation method to study their photo-and thermoluminescent properties. Two crystalline phases were observed in the powders by X-Ray diffraction (XRD), the main phase being Mg 2 P 2 O 7 and the second one thulium phosphate (TmPO 4). The superficial morphology was analyzed by scanning electron microscopy (SEM), which revealed that the powders are agglomerates with an undefined form and grains with non-uniform size distribution. The photoluminescence (PL) emission spectra of Tm3+ doped powders show the 1D 2 → 3F 4 transition, associated with Tm3+ ions, at 452 and 458 nm. The thermoluminescence (TL) properties were analyzed in the undoped and Tm3+ doped powders exposed to 90Sr beta source. The TL glow curve of Tm3+ doped powders exhibits three maxima at about ⁓64–66 °C, ⁓198–202 °C, and ⁓301 °C. The TL dose-response is sub-linear from 0.11 to 0.54 Gy, linear between 0.79 and 24.95 Gy, and supra-linear from 34.99 to 599.95 Gy. Acceptable repeatability with a coefficient of variation of ∼1% was obtained after ten cycles of irradiation and readout. At 63 d of storage, the powders show fading of 30%, and at 1.6 years (585 d), the integrated TL intensity decays by 47%. The kinetic parameters of activation energy and frequency factor were evaluated using the Initial Rise, Booth, Bohun, and Porfianovitch (BBP) and Hoogenstraaten methods and Glow Curve Deconvolution with a general order kinetic model. • Undoped and Tm3+ doped Mg 2 P 2 O 7 powders were synthesized via solvent evaporation method. • Photo- and Thermo-luminescence properties of Mg 2 P 2 O 7: Tm have been studied for the first time. • The Mg 2 P 2 O 7: Tm at 8 mol% shows a high TL response to 90Sr beta radiation. • Kinetic parameters were calculated using Initial Rise, BBP, Hoogenstraaten and Glow Curve Deconvolution methods. [ABSTRACT FROM AUTHOR]