01.1 - Graduação (Sede)
URI permanente desta comunidadehttps://arandu.ufrpe.br/handle/123456789/2
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Resultados da Pesquisa
Item 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/5887132704910210This 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.Item Estudo de propriedades reológicas e espectroscópicas de materiais a base de glutamato monossódico e íons terras raras(2021-07-22) Souza, Danylla Thaiana Teles de Oliveira; Falcão, Eduardo Henrique Lago; http://lattes.cnpq.br/0614524019382645; http://lattes.cnpq.br/5710207526340992In the present work, syntheses of materials formed from commercial monosodium glutamate (GMS) and rare earth ions (RE) La3+ and Y3+ were performed. The methodology used follows that of previous works, carried out by our research group, which obtained new materials from the reaction between GMS and RE ions. This methodology produced transparent, hygroscopic materials with high viscosity. Initially, the 1:1 ratios between TR (La3+ or Y3+) and the ligand (GMS) were chosen for the structure and properties analyses. Subsequently, a small amount (10%) of europium ion (Eu3+) was added to the materials, with the aim of attributing luminescence to the material. For the characterizations rheology measurements and vibrational spectroscopy (infrared and Raman) were used. Through rheological studies it was observed that the viscosity and elasticity parameters vary as the external stress is applied, characterizing the material as a non-Newtonian fluid. The analysis of frequency as a function of storage modulus (G’) and loss modulus (G’’) determined that for high frequencies the system reaches equilibrium, and for low frequencies the system keeps evolving. In addition, it was noted that despite having elasticity, it is not superior to viscosity, with no freezing point. Therefore, the material cannot be classified as a gel. Infrared spectra and Raman spectra were similar in all samples, with minimal variation in the spectra of materials containing yttrium. This suggests that coordination between RE ions and GMS occurs in a similar way.