Group optical basicity and single bond strength of oxide glasses
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2018-01-01
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Abstract
This paper is a review of our recent results in the field of group optical basicity of the oxide glasses. Dimitrov and Komatsu have recently introduced the concept of group (i.e. microscopic) optical basicity, proposed by Duffy and Ingram, to binary R2O (RO) - TeO2 (R = Na, Mg, Sr, Ba, Zn and Pb) and ternary 10R2O.10R'O.80TeO2 (R = Li, Na and K, R'= Mg, Ba and Zn) tellurite glasses based on N4 and N3 fractions of different Te4 and TeO3 groups. In fact, the group basicity of Te4 unit with one non-bridging oxygen (λTeO4 l - = 1.23), Te4 unit without non-bridging oxygen (λTeO4 l = 0.99) and a terminal TeO3 unit with two non-bridging oxygens (λTeO3 l - = 0.82) is evaluated. Equations for evaluation of the theoretical optical basicity Λth(1) of Na2O-B2O3, PbO-B2O3, Na2O-SiO2 and R2ORO- TeO2 glasses are advanced taking into account the contribution of the mole fraction and the group basicity of different structural units, namely BO3, BO4 and SiO4 groups. Equations providing the calculation of the average single bond strength BM-Oof Na2O-B2O3, PbO-B2O3B2O3, Na2OGeO 2, Bi2O3-B2O3 and ZnO-Bi2O3-B2O3 glasses are suggested considering the mole fractions of BO3, B4, Ge4, GeO6, PbO3, Pb4 and PbO6 groups. It is established that there is a general trend of optical basicity increase along with single bond strength decrease in borate-silicate-germanate-tellurite-bismuthate glasses sequence.