Preparation of Novel Materials Using Ordered Structure of Dipo in Metastable Oxides

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The second-order nonlinearity induced by thermal, optical, and electron-beam poling has been studied. For thermally poled glass, surface structure and relaxation phenomenon have been investigated for thermally poled 20WO_3・ 80TeO_2 glass which is known to show large second-order nonlinear susceptibility. X-ray photoelectron spectroscopy reveals that the penetration of Na^+ into the anode-side surface of 20WO_3・80TeO_2 glass occurred during poling since the poling was performed with the 20WO_3・80TeO_2 glass sandwiched in between two commercial borosilicate glasses containing Na^+. The decay of second-harmonic intensity at room temperature is describable in terms of the single exponential function except the glass poled at higher temperature, for which the stretched exponential function is applicable. Also, we found that Ge-As-Se glasses poled by electron-beam poling shows large and stable second-order nonlinearity. It is speculated that photoinduced electronic point defects present in c … More halcogenide glasses are responsible to the second-order nonlinearity. Further, we measured incident light power dependence, incident angle dependence, and polarization dependence of the intensity of second-harmonic wave generated in a composite thin film composed of Cucl nanocrystalline phase and amorphous ITO (indium tin oxide). The experimental data indicate that the direction of anisotropy mainly leading to SHG is perpendicular to the film surface, although the anisotropy the direction of which is parallel to the film surface is present as well. We speculate that the T_d symmetry in crystal structure of CuCl, somewhat orientation of CuCl nanocrystalline phases, the interface between CuCl and ITO phases, and laser-induced structural change of the composite film bring about the SHG with the symmetry observed. On the other hand, for the triboluminescence observed in rare-earth-doped metastable hexacelsian phase, we measured triboluminescence as well as photoluminescence for CaAl_2O_4, SrAl_2O_4, and BaAl_2O_4 polycrystals doped with Eu^<3+> and Eu^<2+>, and clarified that the triboluminescence is caused by Eu^<3+> and Eu^<2+> ions placed in a distorted site such as fractured surface. Less