EDSON LUIS GAIOLLO
3 resultados
Resultados de Busca
Agora exibindo 1 - 3 de 3
Artigo IPEN-doc 27399 Blue-emitting MWO4:Tm3+ (M: Sr, Ba) phosphors prepared by coprecipitation method at room temperature2020 - GAIOLLO, EDSON L.; MOREIRA, RENAN P.; FELINTO, MARIA C.F.C.; BARBOSA, HELLIOMAR P.; PEDROSO, CASSIO C.S.; TEOTONIO, ERCULES E.S.; MALTA, OSCAR L.; BRITO, HERMI F.MWO4 host matrices (M: Sr, Ba) doped with different Tm3+ concentrations (0.02, 0.04, 0.06, 0.08 and 0.10 mol%) have been successfully prepared by the coprecipitation method at room temperature. The as-prepared nanophosphors were characterized by infrared spectroscopy showing intense absorption bands in the range of 700-1000 cm-1 attributed to the symmetrical and asymmetrical stretching vibrations (ν) of the tetrahedral [WO4]2- group. The X-ray diffraction (XRD) measurements reveal the tetragonal scheelite phase with the I41/a (No. 88) space group. The emission spectra of the MWO4:Tm3+ materials are dominated by the highest intensity narrow band of the intraconfigurational 1D2 â 3F4 transitions in the blue region (ca. 456 nm) arising from the Tm3+ ions. Additional low-intensity emission bands originated from the 1G4 â 3H6 (ca. 475 nm), 1G4 â 3F4 (660 nm) and 3H4 â 3H6 (700 nm) transitions are also observed. These optical results indicate that the materials can be used as an alternative to blue-emitting markers.Resumo IPEN-doc 23276 Submicron-crystals of BaWO4:Dy3+ and SrWO4:Dy3+ synthetized by green chemistry method2017 - FELINTO, M.C.F.C.; GAIOLLO, E.; MOREIRA, R.P.; BONTURIM, E.; BARBOSA, H.P.; SILVA, I.G.N.; PEDROSO, C.C.S.; BRITO, H.F.; TEOTONIO, E.E.S.; MALTA, O.M.L.Nowadays, the investigation of oxide based light emitting materials for white lightemitting diodes (w-LEDs) applications have generated interest due to the advantages such as long lifetime, low energy consumption, high luminescence efficiency and environmental friendliness [1]. These qualities make them a strong candidate for the solid state lighting, display devices, optoelectronic devices and light-emitting diodes (LEDs). In this work, we present results of Dy3+: BaWO4 and Dy3+: SrWO4 that present luminescence close to white color (Figure 1) left. They were synthetized using coprecipitation method. The emission spectra exhibit four emission transitions centered at around 486 nm, 576 nm, 665 nm and 760 nm corresponding to the transitions 4F9/2ďŽ6H15/2 (blue), 4F9/2ďŽ6H13/2 (yellow) 4F9/2ďŽ6H11/2 and 4F9/2ďŽ6H9/2 6F11/2 (red) respectively.Among these transitions 4F9/2ďŽ6H15/2 and 4F9/2ďŽ6H13/2 are observed to be strong whereas 4F9/2ďŽ6H11/2 transition is found to be relatively quite weak.The 4F9/2ďŽ6H13/2 transition is hypersensitive in nature and is strongly influenced by the environment around the Dy3+ ion site. It is observed in the luminescence spectra of these materials that the electric dipole transition is dominant compared to the magnetic dipole transition. The CIE diagram show emission close to white (Fig.1 right) for the five composition with little distortion of the color showing the influence of dopant concentration in the color of the emission.Resumo IPEN-doc 22183 Blue luminescence in MWO4:Tmsup(3+) (M= Ba, Sr) phosphors2015 - GAIOLLO, EDSON L.; MOREIRA, RENAN P.; BARBOSA, HELLIOMAR P.; PEDROSO, CASSIO C.S.; RODRIGUES, LUCAS C.V.; MALTA, OSCAR L.; BRITO, HERMI F.; FELINTO, MARIA C.F.C.