| Research Abstract |
The structure of bismuth cuprate, gallate, aluminate, titanate, tellurite and vanadate binary or ternary glasses, which all do not contain "so-called" glass-former at all, and oxynitride glasses has been fully investigated by means of X-ray and neutron radial distribution function analysis, high resolution solid-state multinuclear MAS NMR, and IR and Raman spectroscopy. It has found that the most significant cations, such as Ga^<3+>, Al^<3+>, Ti^<4+>, and Te^<4+>, take a four-fold coordination in glasses. On the other hand, V^<5+> is present not only as VO_5 trigonal bipyramid but also as VO_4 tetrahedra. Pb^<2+> in high-lead glasses is in the forms of PbO_3 and PbO_4 irrespective of glass systems such as silicate, borate and gallate. This means that Pb^<2+>, Bi^<3+> is in the coordination states of BiO_5 and BiO_6, indicating that Bi^<3+> in gallate glasses is rather ionic compared to Pb^<2+>. Search of the coordination state of nitrogen in oxynitride glasses revealed that two-fold ni
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trogen with one non bridging bond as well as three-fold nitrogen is present.
The electrical properties of Na_2O-K_2O-Ga_2O_3-TiO_2 non-silicate non-silicate non-conventional glasses have been studied. It has been recognized that the glass system shows a "mixed alkali effect" although it does not contain any glass formers.
The third order nonlinear optical properties of TeO^2 glasses have been investigated by the THG method. The chi(3) for it was 1.4x10^<-12> esu, which is about 50 times larger than that of silica glass and found to be the largest among the single component glasses to far known. This result really shows that TeO_2 glasses may be one of the most promising candidates as host glasses for nonlinear optical materials. In addition, the nonlinear optical properties of TeO_2-based binary glasses containing transition metal oxides, alkali oxides and alkaline earth metal oxides and so on, have been systematically investigated in order to find out the most important parameters to govern the chi(3) value.
Based on the present results, it becomes possible to design the glasses with desirable properties of bismuth cuprate, gallate, aluminate, titanate, tellurite and vanadate binary or ternary glasses, and oxynitride glasses. Less
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