Abstract Structure and its transformation are examined for amorphous Se-rich AsxSe1-x (0 ≤ x ≤ 0.2) alloys by employment of diffraction and non-diffraction structural probes. It is shown that the molecular structure of amorphous Se (a-Se) on the scale of short-range order is close to that of crystalline phase, while medium-range order differs from the structure of most inorganic glasses and may be placed between three-dimensional network glasses and polymeric ones. Further experiments show the existence of successive phases in laser-induced glass-crystalline transition with pronounced threshold behavior. Below the energy density threshold, Eth, only small changes in the local structure of the system can be detected. Above Eth, the changes were attributed to crystallization transformation. The corresponding Raman spectra reveal transformation of the system from amorphous into the crystalline phase under laser irradiation. In the binary AsxSe1-x glass system, a change of structural regime takes place near the composition x ≈ 0.04. The presence of this topological threshold is established by direct and indirect evidence, such as peculiarities in the composition dependence of the basic parameters for electron diffraction and Raman vibration modes. The peculiarities are caused by the transition from a chain-ring-like structure to preferentially a chain-like structure. Experiments described in this section have shown that Raman technique is a particularly sensitive method to determine the presence of microcrystal's in the glassy matrix. Room-temperature polarized Raman scattering spectra of model glass have been collected. Low-frequency peaks were observed in the spectra. A model is proposed for explanation of their appearance. It is shown clearly that the low-frequency Raman spectra allow determining the conditions at the boundaries, sizes as well as concentration of micro-heterogeneities in non-crystalline materials. It was established earlier that for all amorphous (glassy) materials a low-frequency peak, observed in the corresponding spectral region of Raman scattering and called boson peak, is inherent. This peak is absent in crystals of the same chemical composition and is associated with space correlations on the scale of medium-range order Rc ≈ 10 A. On the contrary, less known is that a boson peak can give important information about the presence of microcrystalline inclusions and heterogeneities in the low-frequency Raman spectra of glasses irrespective to their chemical composition.

中文翻译：

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富硒非晶薄膜的分子结构

摘要 通过使用衍射和非衍射结构探针，研究了非晶富硒 AsxSe1-x (0 ≤ x ≤ 0.2) 合金的结构及其转变。结果表明，非晶Se(a-Se)在短程有序尺度上的分子结构接近于结晶相，而中程有序与大多数无机玻璃的结构不同，可能介于三个之间。维网络玻璃和聚合物玻璃。进一步的实验表明，在具有明显阈值行为的激光诱导玻璃-结晶转变中存在连续相。低于能量密度阈值 Eth，只能检测到系统局部结构的微小变化。高于Eth，变化归因于结晶转变。相应的拉曼光谱揭示了在激光照射下系统从非晶相转变为结晶相。在二元 AsxSe1-x 玻璃系统中，结构状态的变化发生在成分 x ≈ 0.04 附近。这种拓扑阈值的存在是由直接和间接证据确定的，例如电子衍射和拉曼振动模式基本参数的成分依赖性的特性。这些特性是由从链环状结构到优先链状结构的转变引起的。本节中描述的实验表明，拉曼技术是一种特别灵敏的方法，可以确定玻璃基质中微晶的存在。收集了模型玻璃的室温偏振拉曼散射光谱。在光谱中观察到低频峰。提出了一个模型来解释它们的外观。清楚地表明，低频拉曼光谱允许确定非晶材料中的边界条件、尺寸以及微异质性的浓度。早先已经确定，对于所有非晶（玻璃态）材料，在拉曼散射的相应光谱区域中观察到的称为玻色子峰的低频峰是固有的。该峰在具有相同化学成分的晶体中不存在，并且与中等量级 Rc ≈ 10 A 尺度上的空间相关性相关。相反，