Preparação e caracterização de vidros de oxidos de metais pesados para optica não linear

AUTOR(ES)
DATA DE PUBLICAÇÃO

1993

RESUMO

We studied the system TiO2 - BaO - ZnO - B2O3, where we fixed the ZnO and B2O3 compositions, vaying the ratio TiO2/ BaO from 0.87 a 1.76. A super-Kanthal resistance furnace was used to melt the compounds inside alumina crucibles, at about 1200 °C, during 10 minutes. After melting, the glasses were poured out in steel moldes and rapidly cooled by quenching. The glasses obtained were homogeneous, transparent and bubble free. Tehy were characterized by X-ray diffratometry, Fourier transform infrared (FTIR), UV-Vis, dilatometry, density and refractive index. The diffraction curves of all glasses presented typical character of vitreous phase formation. The IR spectra show that the compositions influence both infrared "cut off" and UV- Vis "cut off". From dilatometry was verified that the Td and Tg values are anomalous. The linear dilatation coefficient a presented an anomalous behavior in relation to TiO2 concentrations. The density and refractive index increase with the ratio concentration TiO2/BaO around 1.5. After this point the density and refractive index decreases. The soft point Td increase and the same manner decrease. It is suggested that Ti4+ plays a dual part in the system, assuming a predominantly tetrahedral coordination in the low titania region and a predominantly octahedral co-ordination in the high titania region. By the way, we studied composition influence in structural properties of Bi2O3 in Bi2O3 - B2O3 - PbO - GeO2 glass system, where we fixed two compositions, varying another two. A super-Kanthal resistance furnace was used to melt the powder compound inside alumina crucible, at about 1000 °C, during 30 minutes. After melting, the glasses were poured out in steels moldes. The obtained glasses were characterized by X -ray diffratometry, infrared spectroscopy, dilatometry and linear refractive index. The infrared spectra, coefficient of linear thermal expansion, Td and Tg, show a dependency with increasing of Bi2O3 composition. The linear refractive index was very high. These features were produced by the composition influence of structural properties of Bi2O3 in this glass system

ASSUNTO(S)

vidro espectroscopia de infravermelho otica não-linear oxidos

ACESSO AO ARTIGO

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