Structural and optical studies of the 0.4Li2O-0.6[xB2O3-(1-x)Te2O4] glass system

Referencia Apresentador Autores
Swarup Kundu Kundu, S.(Universidade Federal de São Carlos); Machado, N.P.(Universidade Federal de São Carlos); Rodrigues, A.M.(Universidade Federal de São Carlos); Tellurite glasses are very promising materials for laser and non-linear applications in optics, due to some of their significant characteristic features, such as low melting point, high refractive index and low phonon maxima. TeO2 is known as a conditional glass former, it needs a modifier ion to form the glassy state easily. The formation of glass on two glass formers such as borate glass and tellurite glass is of both scientific and practical interest. The basic structural unit of tellurite glass is TeO4 trigonal bipyramid containing a lone pair of electrons and the structural units take the Te–O–Te bond for glass formation. The introduction of TeO2 into the matrix of alkali borate glasses decreases its hygroscopicity, increases refractive index and enhances the IR transmission. Samples of ternary borotellurite glasses 0.40Li2O-0.60[xB2O3-(1-x)Te2O4], 0?x?1 have been fabricated by melt quenching technique and their physical and optical properties were investigated. The glass transition temperature was found to decrease gradually with the increased content of TeO2. The optical band gap calculated from the transmission data by using Tauc’s plot decreases with increasing of TeO2 content. The validity of Urbach rule was investigated. The infrared reflection spectra recorded in the range of 4000-400 cm-1 showed broad bands which confirm the amorphous nature of the samples. The FTIR results show that [BO3] and [BO4] were among the main structural units in the investigated glasses as well as [TeO3] and [TeO4] groups. Evidence was observed for the presence of boroxol rings in these glasses.
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