Influence of Gd2O3 in the physical and structural properties of new transparent gemanoborate glasses.

Reference Presenter Authors
10-078 Roger Gomes Fernandes Fernandes, R.G.(São Paulo State University); FRANCO, D.F.(Estadual University of São Paulo); Nalin, M.(Instituto de Química, Universidade Estadual Paulista); Magneto-optical materials have been attracting the interest of researchers, both from a fundamental point of view and technological applications. Although magneto-optical effects are more pronounced in crystals, the great difficulty in preparing monocrystals with practical dimensions limits their use in photonic devices. An effective alternative is to use transparent glasses and glass-ceramics containing paramagnetic ions. However, in order to achieve the desired properties, it is necessary to understand the structural modifications as well as the chemical environment occupied by these ions in the glass matrix. In this work, a series of new transparent germanoborate glasses containing gadolinium oxide has been prepared and characterized with respect to their thermal, structural and spectroscopic properties. In this system, the glasses matrices accepted up to 20% mol of Gd2O3. Raman spectra were analyzed and identified that increasing Gd2O3 content promote a progressive depolymerization of 6-member GeO4 rings concomitants with an increase of GeO4 tetrahedra units with 1 non-briding oxygen. DSC curve of all sample showed a crystalline phase with its maximum near 900 °C, besides, appear an exothermic event near 750 °C for samples with concentrations higher than 15% of Gd2O3. Glass with 5% of Gd2O3 showed a high thermal stability against crystallization of 273 °C, which progressively decreases to 165 °C for samples with higher Gd2O3 content. Monolithic samples were heat treated for crystallization at 10ºC/min in the electrical furnace up to different maximum temperatures, set according to DSC crystallization peaks. The microstructure evolution due to crystallization was evaluated by optical microscopy. The crystalline phases, as well as the distribution of the paramagnetic ions, were analyzed by XRD and EDX, respectively.
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