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首页> 外文期刊>Journal of Non-Crystalline Solids: A Journal Devoted to Oxide, Halide, Chalcogenide and Metallic Glasses, Amorphous Semiconductors, Non-Crystalline Films, Glass-Ceramics and Glassy Composites >Role of sol-gel networking and fluorine doping in the silica Urbach energy
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Role of sol-gel networking and fluorine doping in the silica Urbach energy

机译：溶胶-凝胶网络和氟掺杂在二氧化硅Urbach能量中的作用

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摘要

We present the results of the analysis of the ultraviolet (UV) absorption edge of fluorine-modified sol-gel silica. UV transmission data, obtained by means of synchrotron radiation, have been analyzed in the spectral range 7.5-8.5 eV, with a spectral resolution of about 10 meV. Data on silica samples with different F content (from 0 to few 10- 1 mol%) have been analyzed and compared with literature data on quartz and pure synthetic commercial silica. The analysis allows us to discriminate between the effects of the fluorine addition and those ascribable to structural peculiarities of the sol-gel networking. The estimated Urbach energy E_U(T = 0) ranges between 45 and 55 meV, higher that in crystalline quartz and lower than in commercial synthetic silica. The study of the temperature dependence of E_U(T) shows that the fluorine modification of the silica network causes the lowering of the static disorder and the widening of the energy gap. However, there is also a relevant effect of the production process, since sol-gel silica samples show lower E_U values with respect to other types of silica, quite independently of the fluorine content. The analysis of the Raman spectra however shows that the starting amount of fluorine-modified molecular precursor influences the network condensation process, independently of the final fluorine content into the matrix.
机译：我们介绍了氟改性的溶胶-凝胶二氧化硅的紫外线（UV）吸收边缘的分析结果。通过同步加速器辐射获得的紫外线透射数据已在7.5-8.5 eV的光谱范围内进行了分析，光谱分辨率约为10 meV。分析了不同F含量（0至10-1 mol％）的二氧化硅样品的数据，并将其与有关石英和纯合成商品二氧化硅的文献数据进行了比较。通过分析，我们可以区分氟添加的影响与归因于溶胶-凝胶网络结构特殊性的影响。估计的Urbach能量E_U（T = 0）在45到55 meV之间，高于晶体石英，低于商业合成二氧化硅。对E_U（T）的温度依赖性的研究表明，二氧化硅网络的氟改性导致静电无序的降低和能隙的扩大。但是，由于溶胶-凝胶二氧化硅样品相对于其他类型的二氧化硅显示出较低的E_U值，而与氟含量完全无关，因此生产过程也会产生相关影响。然而，对拉曼光谱的分析表明，氟改性分子前体的起始量影响网络缩合过程，而与基质中最终氟的含量无关。

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