Structure and the low temperature properties of amorphous solids
Structure and the low temperature properties of amorphous solids
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非晶态固体的结构和低温性能
DOI：
10.1016/0022-3093(78)90108-4
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发表时间：
1978
期刊：
影响因子：
--
通讯作者：
W. Phillips
中科院分区：
文献类型：
--
作者：
W. Phillips
对无定形固体低温特性的讨论可以方便地分为两部分，分别对应于 2 到 50 K 之间的温度范围和低于 2 K 的温度范围。在 2 K 以上，绝大多数玻璃的热容和导热率以类似的方式表现，尽管它们随成分而系统地变化。这些特性几乎不受玻璃形成方法变化的影响，并且被认为反映了结构的固有低频振动模式的行为。这种模式只能通过指定大约十个（或更多）原子的运动来描述，这与典型红外或拉曼光谱中重要的振动模式不同，后者通常可以通过指定少至两个原子的相对运动来描述。由此可见，与光谱技术相比，低温效应对于局部结构的探测灵敏度要低得多。在 1 至 50 K 范围内，不同结构之间的声学特性显示出较大的差异，但同样不是结构的精确探针。低于 2 K，热学和声学特性可能会因玻璃的制备方法或杂质水平而有很大差异。然而，大量氧化物、硫族化物和金属玻璃的一般特征惊人地相似。在不完美的晶体材料中也发现了类似的热特性，这表明这种效应是短程无序的一个特征，它不特定于任何一种结构类型。在某些情况下，这一特征已被确定为结构内特定位点上一个或两个原子的重排，尽管其影响取决于位点的浓度如此之小，一般来说识别起来很困难。事实上，关于这些热和声学特性的一个重要问题是，这些效应是否是内在的，即它们会在玻璃的完全协调的随机网络模型中发生，或者是否必须存在以不完全协调或杂质形式存在的缺陷。无论哪种情况，这种效应与结构的关系仍然是混乱的。
A discussion of the low temperature properties of amorphous solids can conveniently be divided into two parts corresponding to the temperature range between 2 and 50 K, and that below 2 K. Above 2 K the heat capacity and thermal conductivity behave in a similar way in the overwhelming majority of glasses, although they vary systematically with composition. These properties are little affected by changes in the method of formation of the glass, and are believed to reflect the behaviour of the intrinsic low frequency vibrational modes of the structure. Such modes can be described only be specifying the motion of about ten (or more) atoms, unlike the vibrational modes important in a typical infrared or Raman spectrum which can often be described by specifying the relative motion of as few as two atoms. It follows that the low temperature effects are much less sensitive probes of local structure than the spectroscopic techniques. The acoustic properties show wider variations between different structures in the range 1 to 50 K, but again are not precise probes of the structure.Below 2 K, the thermal and acoustic properties can vary considerably with the method of preparation or the impurity level of a glass. However, the general features are surprisingly similar in a large number of oxide, chalcogenide and metallic glasses. Similar thermal properties have been seen in imperfect crystalline materials, suggesting that such effects are a feature of a short-range disorder which is not specific to any one type of structure. In some cases this feature has been identified as the rearrangement of one or two atoms at particular sites within the structure, although the effects depend on such small concentrations of sites that in general identification is difficult. Indeed, one important question concerning these thermal and acoustic properties is whether the effects are intrinsic, in the sense that they would occur in say a fully coordinated random network model of a glass, or whether defects, in the form of incomplete coordination, or impurities, must be present. In either case the relation of such effects to structure is still confused.