Atsushi Ohtsuka

Raman spectra of MO1/2TeO2 (M = Li, Na, K, Rb, Cs and Tl) glasses

The structure of MO 1/2 TeO 2 (M = Li, Na, K, Rb, Cs and Tl) binary glasses has been studied by means of Raman spectroscopy. The glasses having low alkali content have a continuous network constructed by sharing corners of TeO 4 trigonal bipyramids (tbps) and TeO 3 + 1 polyhedra having one non-bridging oxygen atom (NBO). In the glasses containing 20–30 mol% alkali oxide, TeO 3 trigonal pyramids (tps) having NBOs are formed in the continuous network. When alkali content exceeds 30 mol%, isolated structural units, such as Te 2 O 2− 5 ion, coexist in the continuous network. The fraction of TeO 4 tbps decreases with increasing alkali content. The glasses, which contain nearly 50 mol% alkali oxide, are composed of a continuous network constituted by TeO 3 + 1 polyhedra and TeO 3 tps, and of isolated structural units, such as Te 2 O 2− 5 and TeO 2− 3 ions. The structure of thallium tellurite glasses having less than 30 mol% TlO 1/2 is similar to that of alkali tellurite glasses containing equal amounts of MO 1/2 . The fraction of TeO 3 tps having NBOs in the thallium tellurite glasses, when TlO 1/2 content is equal to or higher than 40 mol%, is larger than that in the corresponding alkali tellurite glasses. In the 66TlO 1/2 ·34TeO 2 glass, most of tellurium atoms are in a form of isolated TeO 2− 3 ion. A new hypothesis is also given for a mechanism for the basic structural changes in the tellurite glasses.

Raman spectra of MOTeO2 (M = Mg, Sr, Ba and Zn) glasses

Abstract The structure of MOTeO 2 (M = Mg, Sr, Ba and Zn) glasses was investigated by Raman spectroscopy. The glasses with low BaO have a continuous network constructed by sharing corners of TeO 4 trigonal bipyramids and TeO 3+1 polyhedra having one non-bridging oxygen (NBO) atom. In the glasses, TeO 3 trigonal pyramids having NBO atoms are also formed in the continuous network. In 36BaO · 64TeO 2 glass, isolated structural fragments, such as TeO 3 2− and Te 3 O 8 4− ions, coexist with the continuous network. The structure of MgOTeO 2 glasses is different from that of the BaOTeO 2 glasses. In glasses containing about 40 mol% MgO, a (Te 3 O 8 4− ) n unit, in which n is relatively small, is formed. The fraction of tellurium atoms forming TeO 3 trigonal pyramids increases with MgO content. When MgO exceeds 40 mol%, isolated structural units, such as TeO 3 2− and Te 3 O 8 4− ions, will be formed in glasses. The SrOTeO 2 and ZnOTeO 2 glasses have the same structure as the BaOTeO 2 and MgOTeO 2 glasses, respectively.

Raman spectra of BO32TeO2 glasses

Abstract The structure of BO 3 2  TeO 2 glasses was investigated by Raman spectroscopy. Glasses with low BO 3 2 content have a continuous network structure composed mainly of TeO4 trigonal bipyramids. In the network, a considerable fraction of boron atoms form BO4 groups and a small fraction of boron atoms form B2O5 and BO3 groups. With increase of BO 3 2 content, both trigonally coordinated tellurium and tetrahedrally coordinated boron atoms are increased in numbers. Condensed borate groups are formed by condensation of BO4, B2O5 and BO3 groups. In glasses containing nearly 50 mol% BO 3 2 , a continuous network is constituted by tellurite clusters, B2O5, BO3, BO4 and condensed borate groups. The behavior of boron in the BO 3 2  TeO 2 system is discussed on the basis of TeO and BO bond strengths.

The application of chemical effects in high resolution X-ray spectrometry

Abstract Chemical effects on Mn K α Mn K β , Cr K β and Sn L β 2 were investigated with a high resolution two-crystal X-ray spectrometer. The width of Mn K α 1 and the energy shifts of Mn K β , Cr K β and Sn L β 2 were found to be dependent on the chemical state, especially on the oxidation number of X-ray emitting atoms. The changes in the Mn K α 1 width and in the Mn K β , Cr K β and Sn L β 2 , energy shifts were large enough to be used for identification of the oxidation states of these elements in various compounds. The phenomena were applied to the chemical state analysis of manganese and chromium in inorganic pigments, chromium and tin in glass, and tin in organic catalysts.

Raman spectra of BO 3 2 TeO 2 glasses

Abstract The structure of BO 3 2  TeO 2 glasses was investigated by Raman spectroscopy. Glasses with low BO 3 2 content have a continuous network structure composed mainly of TeO4 trigonal bipyramids. In the network, a considerable fraction of boron atoms form BO4 groups and a small fraction of boron atoms form B2O5 and BO3 groups. With increase of BO 3 2 content, both trigonally coordinated tellurium and tetrahedrally coordinated boron atoms are increased in numbers. Condensed borate groups are formed by condensation of BO4, B2O5 and BO3 groups. In glasses containing nearly 50 mol% BO 3 2 , a continuous network is constituted by tellurite clusters, B2O5, BO3, BO4 and condensed borate groups. The behavior of boron in the BO 3 2  TeO 2 system is discussed on the basis of TeO and BO bond strengths.

Raman spectra of glasses

Abstract The structure of BO 3 2  TeO 2 glasses was investigated by Raman spectroscopy. Glasses with low BO 3 2 content have a continuous network structure composed mainly of TeO4 trigonal bipyramids. In the network, a considerable fraction of boron atoms form BO4 groups and a small fraction of boron atoms form B2O5 and BO3 groups. With increase of BO 3 2 content, both trigonally coordinated tellurium and tetrahedrally coordinated boron atoms are increased in numbers. Condensed borate groups are formed by condensation of BO4, B2O5 and BO3 groups. In glasses containing nearly 50 mol% BO 3 2 , a continuous network is constituted by tellurite clusters, B2O5, BO3, BO4 and condensed borate groups. The behavior of boron in the BO 3 2  TeO 2 system is discussed on the basis of TeO and BO bond strengths.