Calculation of the Entropies of Lattice Defects
Calculation of the Entropies of Lattice Defects
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晶格缺陷熵的计算
DOI：
10.1103/physrev.99.1085
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发表时间：
1955
期刊：
影响因子：
--
通讯作者：
E. Wajda
中科院分区：
文献类型：
--
作者：
H. B. Huntington;G. Shirn;E. Wajda
晶格缺陷的熵在这里比以前更详细地考虑。计算是为了估计与晶格缺陷有关的固有熵，如间隙和空位，以及与空位和环扩散的活化配合物。目前的应用是fcc金属和一个非常简化的力模型只表示封闭壳，离子核排斥铜已被使用。问题在于评估每一缺陷引入后晶格振动的变化。该方法是第一个近似考虑缺陷周围的局部振动，将其与距离缺陷相当距离的弹性振动分开。只有在远离缺陷的区域，熵贡献才总是正的。零压力的表面条件引入了一个术语来减少“局部”振动的影响。一般来说，在那些原子拥挤的构型中固有熵比那些原子有更大自由体积的构型要小。
The entropy of lattice defects are here considered in somewhat greater detail than previously. Calculations are out to estimate the intrinsic entropies associated with such lattice defects as interstitialcies and vacancies, and with the activated complexes of vacancy and ring diffusion. The present application is to fcc metals and a very simplified force model representing only the closed-shell, ion-core repulsions of copper has been used. The problem consists in evaluating the change of lattice vibrations with the introduction of each defect. The method is in a first approximation to consider vibrations localized around the defect as separate from elastic vibrations at appreciable distance from the defect. Only in the region far from the defect is the entropy contribution always positive. The surface condition of zero pressure introduces a term which reduces the effect of the" localized" vibrations. In general the intrinsic entropy is less positive for those configurations where there is crowding of the atoms than for those configurations where the atoms have greater free volume.