Vibrational densities of states and network rigidity in chalcogenide glasses.
Vibrational densities of states and network rigidity in chalcogenide glasses.
复制标题
硫系玻璃中的振动态密度和网络刚性。
DOI：
10.1103/physrevb.44.94
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发表时间：
1991
期刊：
影响因子：
--
通讯作者：
Mutka
中科院分区：
文献类型：
--
作者：
Kamitakahara;Cappelletti;Boolchand;Halfpap;Gompf;Neumann;Mutka
Vibrational spectra have been measured by neutron scattering for a series of Se-Ge and Se-As-Ge glasses, spanning a wide range in composition and, consequently, in network connectivity. Low-frequency floppy'' modes arising from underconstrained atomic configurations have been observed, in qualitative agreement with recent theories of the dynamics of network glasses. The number of floppy modes was found to depend only on the average coordination number {l angle}{ital r}{r angle}. There is some indication of a rigidity percolation threshold at {l angle}{ital r}{r angle}{approx}2.4, but the effect in the vibrational densities of states is not dramatic. The wave-vector dependence of the scattering at low vibrational energies ({approx}2 meV) is acoustic-phonon-like. Specific heats {ital C} calculated from the measured densities of states show a strongly composition-dependent bump in {ital C}/{ital T}{sup 3} near 4 K, in accord with experiment.
Vibrational spectra have been measured by neutron scattering for a series of Se-Ge and Se-As-Ge glasses, spanning a wide range in composition and, consequently, in network connectivity. Low-frequency floppy'' modes arising from underconstrained atomic configurations have been observed, in qualitative agreement with recent theories of the dynamics of network glasses. The number of floppy modes was found to depend only on the average coordination number {l angle}{ital r}{r angle}. There is some indication of a rigidity percolation threshold at {l angle}{ital r}{r angle}{approx}2.4, but the effect in the vibrational densities of states is not dramatic. The wave-vector dependence of the scattering at low vibrational energies ({approx}2 meV) is acoustic-phonon-like. Specific heats {ital C} calculated from the measured densities of states show a strongly composition-dependent bump in {ital C}/{ital T}{sup 3} near 4 K, in accord with experiment.