Navegando por Autor "Valença, Maria Eduarda de Goes"

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Síntese e caracterização de novos materiais luminescentes à base de glutamato e ítrio
(2019-12-09) Valença, Maria Eduarda de Goes; Falcão, Eduardo Henrique Lago; Vila Nova, Suzana Pereira; http://lattes.cnpq.br/7716018904442218; http://lattes.cnpq.br/0614524019382645; http://lattes.cnpq.br/5887132704910210
This work focuses on the synthesis of new luminescent materials using as precursors the commercial monosodium glutamate and rare earth ions (yttrium, neodymium and europium), which presented a gel aspect. The methodology used follows a previous work, in which a material containing glutamate and neodymium was obtained. The hypothesis raised was that it would be possible to obtain a similar material replacing the neodymium by the yttrium, based on the similar chemical properties between these two metals. This substitution is justified by the fact that neodymium is about three times more expensive than yttrium. Initially, materials containing only glutamate and yttrium were obtained, which presented a gel aspect, varying the proportions between the metal and the ligand. The proportion (in millimol) that contains the smallest amount of metal in relation to the binder and still forms the material with gel aspect is 1:10, metal-ligand, respectively. However, the proportion chosen to continue the work was 1:5, because it was also employed in the previous work. To the yttrium and glutamate gel were added varying amounts (1 to 50% mol) of neodymium and europium in order to assign luminescent properties to the material. The characterization of the materials included the techniques of infrared spectroscopy, Raman spectroscopy and luminescence spectroscopy. The infrared spectra of the material containing only yttrium and glutamate showed a profile similar to those of the material containing only neodymium and glutamate. The materials containing yttrium, neodymium and glutamate also followed the same profile, while those containing yttrium, europium and glutamate varied minimally. The Raman spectra of the yttrium and glutamate materials coincided with those of neodymium and glutamate. However, those of europium and glutamate materials varied substantially compared to the others. This suggests that the yttrium coordinates to the glutamate similarly to the neodymium does, but the europium coordinates differently. The luminescence spectra were obtained for the material containing only neodymium and for the material containing yttrium and neodymium. The characteristic Nd3+ transitions were observed, and the intensities varied according to the amount of neodymium present in each sample.