AsxS1-x二元系统玻璃transition temperatures中的中间相、网络分层、玻色子和松弛模及组分趋势
Intermediate phase, network demixing, boson and floppy modes, and compositional trends in glass transition temperatures of binary AsxS1-x system
摘要：
本文用调制DSC、Raman散射、红外反射和摩尔体积实验等方法，在较宽的组成范围（8%<x<41%）内，对二元As_（xS_{1-x}）玻璃的结构进行了研究。我们在量热实验中观察到一个可逆性窗口，它允许固定三个弹性相;在x<22.5%时是柔性的，在22.5%<x<29.5%范围内是中间相（IP），在x> 29.5%时是应力刚性的。拉曼散射的第一性原理集团计算表明存在金字塔（PYR，As（S1/2）3）和准四面体（QT，S=As（S1/2）3）的本地结构。QT单位浓度在IP中显示出全局最大值，而PYR单位的浓度变得与相位中QT单位的浓度相当，这表明这两种局部结构都对IP的宽度有贡献。在硫化物中的IP质心显着转移到较低的As含量x比相应的硒化物，一个功能与过量的硫族元素部分地从硫化物中的骨干分离，但形成的骨干硒化物的一部分。这些想法得到证实的比例较大的自由体积的硫化物比硒化物，以及没有化学键强度缩放的Tg之间的As-硫化物和As-硒化物。随着玻璃中As含量从x = 20%降低到8%，低频拉曼模式的散射强度线性增加，斜率接近刚性理论预测的柔性玻璃中的软模分数。这些结果表明，松弛模式有助于在低频下观察到的过量振动。在中间和应力刚性弹性阶段，低频拉曼模式持续存在，并被确定为玻色子模式。一些后果，目前的研究结果对这些玻璃的光电性能的评论。
英文摘要：
The structure of binary As_xS_{1-x} glasses is elucidated using modulated-DSC, Raman scattering, IR reflectance and molar volume experiments over a wide range (8%<x<41%) of compositions. We observe a reversibility window in the calorimetric experiments, which permits fixing the three elastic phases; flexible at x<22.5%, intermediate phase (IP) in the 22.5%<x<29.5% range, and stressed-rigid at x>29.5%. Raman scattering supported by first principles cluster calculations reveal existence of both pyramidal (PYR, As(S1/2)3) and quasi-tetrahedral(QT, S=As(S1/2)3) local structures. The QT unit concentrations show a global maximum in the IP, while the concentration of PYR units becomes comparable to those of QT units in the phase, suggesting that both these local structures contribute to the width of the IP. The IP centroid in the sulfides is significantly shifted to lower As content x than in corresponding selenides, a feature identified with excess chalcogen partially segregating from the backbone in the sulfides, but forming part of the backbone in selenides. These ideas are corroborated by the proportionately larger free volumes of sulfides than selenides, and the absence of chemical bond strength scaling of Tgs between As-sulfides and As-selenides. Low-frequency Raman modes increase in scattering strength linearly as As content x of glasses decreases from x = 20% to 8%, with a slope that is close to the floppy mode fraction in flexible glasses predicted by rigidity theory. These results show that floppy modes contribute to the excess vibrations observed at low frequency. In the intermediate and stressed rigid elastic phases low-frequency Raman modes persist and are identified as boson modes. Some consequences of the present findings on the optoelectronic properties of these glasses is commented upon.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
