Emergence of crystal-like atomic dynamics in glasses at the nanometer scale.
Emergence of crystal-like atomic dynamics in glasses at the nanometer scale.
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DOI：
10.1103/physrevlett.110.185503
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发表时间：
2013-05
影响因子：
8.6
通讯作者：
G. Baldi;M. Zanatta;E. Gilioli;V. Milman;K. Refson;B. Wehinger;B. Winkler;A. Fontana;G. Monaco
中科院分区：
文献类型：
--
作者：
G. Baldi;M. Zanatta;E. Gilioli;V. Milman;K. Refson;B. Wehinger;B. Winkler;A. Fontana;G. Monaco
将永久致密化石英玻璃的振动动力学与α-石英多晶的振动动力学进行比较，α-石英多晶是具有相同密度和局部结构的石英多晶型物。非弹性X射线散射实验和从头算数值计算的结合使用提供了令人信服的证据的过渡，在玻璃中，从各向同性的弹性响应在长波长的微观制度的波长降低到低于几个纳米的特征长度λ，对应于约20原子间的距离。在微观制度的玻璃振动非常类似的多晶体，与激发有关的晶体的声学和光学模式。假设玻璃的弹性模量呈现平均尺寸为a ~ π/2 π的空间不均匀性，得到了实验结果的一致描述。
The vibrational dynamics of a permanently densified silica glass is compared to the one of an α-quartz polycrystal, the silica polymorph of the same density and local structure. The combined use of inelastic x-ray scattering experiments and ab initio numerical calculations provides compelling evidence of a transition, in the glass, from the isotropic elastic response at long wavelengths to a microscopic regime as the wavelength decreases below a characteristic length ξ of a few nanometers, corresponding to about 20 interatomic distances. In the microscopic regime the glass vibrations closely resemble those of the polycrystal, with excitations related to the acoustic and optic modes of the crystal. A coherent description of the experimental results is obtained assuming that the elastic modulus of the glass presents spatial heterogeneities of an average size a ~ ξ/2 π.