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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 >Interpretation and modeling of IR-reflectance spectra of glasses considering medium range order
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Interpretation and modeling of IR-reflectance spectra of glasses considering medium range order

机译：考虑中程阶数的玻璃的红外反射光谱的解释和建模

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Conventional qualitative and quantitative IR-reflectance spectrum interpretation of glasses is discussed in light of new findings on the optics of polycrystalline materials and the close relation of the structure of crystallites and regions of medium range order in related glasses. According to these findings, a glass spectrum must not be compared in general with the spectrum of a related polycrystalline material, if the crystallite size exceeds the resolution limit of light. As a consequence of the similarities between the spectra of glassy and related polycrystalline compounds (optically small crystallites) and based on medium range order, the macroscopic optical properties of glasses result not only from disorder and fluctuations, but also from an orientational average of the optical properties of the medium range regions similar to the macroscopic optical properties of polycrystalline materials. Consequently, the assumption of cubic symmetry, which underlies all conventional types of dispersion analysis used for glasses, is inadequate. Based on ARIT (average refractive index theory), [Appl. Spectrosc. 56 (2002) 1194], which permits modeling the optical properties of polycrystalline materials with optically small crystallites, a method is proposed to generate artificial glass spectra from single crystal data. This method is particularly useful if polycrystalline bulk samples with optically small crystallites are not available, since it enables us to determine glass structure on a semi-quantitative level by comparing measured and artificial spectra. The value of the approach is demonstrated for fresnoite glass (Ba2TiSi2O8), Sr-fresnoite glass (Sr2TiSi2O8) and Ge-fresnoite glass (Ba2TiGe2O8). An important consequence of the assumption of an orientational average of the microscopic optical properties of medium range order regions is the prediction of the occurrence of mixed TO-LO modes in glasses. This is confirmed by the resemblance between peak shapes of model oscillators with large oscillator strengths and small damping constants and the prominent high wave number feature of vitreous silica. (C) 2003 Published by Elsevier B.V. [References: 31]
机译：鉴于对多晶材料光学的新发现以及相关玻璃中微晶结构和中程有序区域的密切关系，讨论了玻璃的常规定性和定量红外反射光谱解释。根据这些发现，如果微晶尺寸超过光的分辨率极限，则通常不能将玻璃光谱与相关多晶材料的光谱进行比较。由于玻璃态和相关的多晶化合物（光学上小的微晶）光谱之间的相似性，并且基于中等范围的阶数，玻璃的宏观光学特性不仅来自无序和起伏，而且还来自光学取向的平均值。中等范围区域的性质类似于多晶材料的宏观光学性质。因此，基于立方对称性的假设是不充分的，而这种假设是所有常规类型的玻璃色散分析的基础。基于ARIT（平均折射率理论），[Appl。光谱。 56（2002）1194]，其允许用光学小的微晶对多晶材料的光学特性进行建模，提出了一种从单晶数据生成人工玻璃光谱的方法。如果无法获得具有光学上小的微晶的多晶大块样品，则此方法特别有用，因为它使我们能够通过比较实测光谱和人工光谱来确定半定量玻璃结构。证明了该方法的价值，适用于贝氏体玻璃（Ba2TiSi2O8），锶锶微晶石玻璃（Sr2TiSi2O8）和锗钙钛矿玻璃（Ba2TiGe2O8）。假设中等范围级区域的微观光学特性的取向平均值的重要结果是预测玻璃中混合TO-LO模式的出现。振荡器强度大，阻尼常数小的模型振荡器的峰形与玻璃状石英的高波数特征之间的相似性证实了这一点。 （C）2003年，Elsevier B.V.出版[参考文献：31]

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