Navegando por Autor "Gurgel, G. M."
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Artigo Evaluation of morphology and photoluminescent properties of PbMoO4 crystals by ultrasonic amplitude(Springer, 2016-12-30) Paskocimas, Carlos Alberto; Gurgel, G. M.; Lovisa, Laura Ximena; Conceição, O. L. A.; Li, Maximo Siu; Silva, Elson Longo da; Motta, Fabiana Villela da; Delmonte, Maurício Roberto BomioLead molybdate (PbMoO4) crystals were synthesized by the facile sonochemical method at 20 kHz frequency with a variable ultrasonic amplitude and synthesis time. These crystals were structurally characterized by X-ray diffraction (XRD). Field emission scanning electron microscopy images were employed to observe the evolution of the crystal growth process. XRD patterns indicate that these crystals have a scheelite-type tetragonal structure. The growth mechanism of PbMoO4 crystal was proposed to explain the development stages starting with precipitates formed by particles with disordered growth to form dendritic structures. The effect of the amplitude processing applied was rather significant for the size range of the particles produced. The optical properties were analyzed by ultraviolet–Visible (UV–Vis) absorption spectroscopy and photoluminescence (PL) measurements. The spectrum shows that the sample has a typical green emission. The origin of the PL emission spectrum of the metal molybdates might be ascribed to the charge-transfer transitions within [MoO4] clustersArtigo Photoluminescence properties of (Eu, Tb, Tm) co-doped PbMoO4 obtained by sonochemical synthesis(Elsevier, 2017-04-05) Gurgel, G. M.; Lovisa, Laura Ximena; Pereira, Laurenice Martins; Motta, Fabiana Villela da; Li, Maximo Siu; Silva, Elson Longo da; Paskocimas, Carlos Alberto; Delmonte, Maurício Roberto BomioThe PbMoO4 co-doped with Tm3+, Tb3+ Eu3+ with scheelita structure was synthesized by the sonochemical method. The photoluminescent properties, structural and color coordinates emitted by phosphors were investigated. The structural analysis of the crystal and the changes in lattice parameters confirm that the rare earth ions (RE3+) were successfully introduced into the host of the PbMoO4. The relationship between energy gap (Egap) and the concentration of RE3+ ions was also discussed, the Egap is significantly influenced by the degree of structural order-disorder present in the crystal lattice. The PbMoO4:RE3+ shows light emission in green. Under UV excitation, Photoluminescence (PL) shows a broad band centered at 520 nm and smaller bands belonging to transitions of RE3+: 1G4 → 3 F4 and 1D2 → 3H4 at 480 and 533 nm (Tm3+), 5D4 → 7 Fj (j = 6, 5) at 493 and 550 nm (Tb 3+) 5D0 → 7Fj (j = 1, 2, 4) 593, 615 and 702 nm (Eu3+)Artigo Photoluminescence properties of (Eu, Tb, Tm) co-doped PbMoO4 obtained by sonochemical synthesis(Elsevier, 2017-04-05) Paskocimas, Carlos Alberto; Lovisa, Laura Ximena; Gurgel, G. M.; Pereira, Laurenice Martins; Motta, Fabiana Villela da; Silva, Elson Longo da; Li, Maximo Siu; Delmonte, Maurício Roberto BomioThe PbMoO4 co-doped with Tm3+, Tb3+ Eu3+ with scheelita structure was synthesized by the sonochemical method. The photoluminescent properties, structural and color coordinates emitted by phosphors were investigated. The structural analysis of the crystal and the changes in lattice parameters confirm that the rare earth ions (RE3+) were successfully introduced into the host of the PbMoO4. The relationship between energy gap (Egap) and the concentration of RE3+ ions was also discussed, the Egap is significantly influenced by the degree of structural order-disorder present in the crystal lattice. The PbMoO4:RE3+ shows light emission in green. Under UV excitation, Photoluminescence (PL) shows a broad band centered at 520 nm and smaller bands belonging to transitions of RE3+: 1G4 → 3F4 and 1D2 → 3H4 at 480 and 533 nm (Tm3+), 5D4 → 7Fj (j = 6, 5) at 493 and 550 nm (Tb 3+) 5D0 → 7Fj (j = 1, 2, 4) 593, 615 and 702 nm (Eu3+)