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High-frequency dynamics of vitreous GeSe_2

机译：玻璃态GeSe_2的高频动力学

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摘要

The vibrational dynamics of vitreous germanium diselenide (v-GeSe_2), an amorphous glass belonging to the family of continuous random network forming glasses, has been investigated by means of inelastic neutron scattering. We employed three different neutron spectrometers, each of them providing different energy resolutions and spanning different portions of the energy-wave-vector (hw,Q) plane, which partially overlap so that complementary information can be obtained. Two well-defined peaks are resolved in the dynamic structure factor in a broad Q region, below and above the position of the first sharp diffraction peak in the static structure factor. The low-lying excitation is nondispersive and located around the boson peak frequency. The high-frequency mode presents a pseudoperiodic behavior and it can be associated to the high-frequency counterpart of the longitudinal acoustic (LA) mode. In the low-Q region this mode shows a positive dispersion of its apparent sound velocity and an attenuation which follows a Q~2 law. The combined use of a set of appropriate instruments allows an accurate determination of the nonergodicity parameter f(Q). The LA dispersion curve of v-GeSe_2 is similar to that measured in other glasses where a second excitation appears in the spectra. On the contrary other glass forming materials, where this second mode is not detected, present a sinusoidal-like dispersion curve with a deeper minimum in the second pseudo-Brillouin zone.
机译：通过非弹性中子散射研究了二硒化锗玻璃（v-GeSe_2）的振动动力学，该非晶玻璃属于连续随机网络形成玻璃家族。我们采用了三种不同的中子能谱仪，它们各自提供了不同的能量分辨率，并且跨越了能量波矢量（hw，Q）平面的不同部分，这些部分重叠，从而可以获得互补信息。在动态结构因子中，在静态结构因子中第一个尖锐衍射峰的位置下方和上方的宽Q域中，解析出两个明确定义的峰。低层激发是非分散的，位于玻色子峰值频率附近。高频模式呈现伪周期性行为，并且可以与纵向声学（LA）模式的高频对应项相关联。在低Q区域，此模式显示出其表观声速的正色散和遵循Q〜2定律的衰减。一组适当工具的组合使用可以准确确定非遍历性参数f（Q）。 v-GeSe_2的LA色散曲线类似于在光谱中出现第二次激发的其他玻璃中测得的色散曲线。相反，未检测到该第二模式的其他玻璃形成材料呈现出第二伪布里渊区中具有更深最小值的正弦曲线状色散曲线。

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  • 来源
    《Physical review》 |2010年第11期|p.115201.1-115201.9|共9页
  • 作者

    L. Orsingher; rnG. Baldi; rnA. Fontana; rnL. E. Bove; rnT. Unruh; rnA. Orecchini; rnC. Petrillo; rnN. Violini; rnF. Sacchetti;

  • 作者单位

    Physics Department, Trento University, 38050 Povo, Trento, Italy;

    rnEuropean Synchrotron Radiation Facility, BP 220, 38043 Grenoble, France and IPCF-CNR, UOS di Roma, 00185 Roma, Italy;

    rnPhysics Department, Trento University, 38050 Povo, Trento, Italy and IPCF-CNR, UOS di Roma, 00185 Roma, Italy;

    rnDPMD-IMPMC, UMR 7590, Universite Pierre et Marie Curie (UPMC), 140, F-75015 Paris, France;

    rnForschungsneutronenquelle Heinz-Maier-Leibnitz (FRM II), Technische Universitaet Muenchen, 85747 Garching, Germany;

    rnPhysics Department, Perugia University, 06100 Perugia, Italy;

    rnPhysics Department, Perugia University, 06100 Perugia, Italy;

    rnPhysics Department, Perugia University, 06100 Perugia, Italy;

    rnPhysics Department, Perugia University, 06100 Perugia, Italy;

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  • 关键词

    disordered solids;

    机译：无序固体;

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