Nonstoichiometry in line compounds
Nonstoichiometry in line compounds
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线性化合物中的非化学计量
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
G. Collins
中科院分区：
文献类型：
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作者：
G. Collins
组成场窄于约 1 at.% 并在二元相图中显示为线的相通常被认为具有与组成无关的性质。最近对制备成具有相反相界成分的样品对的测量说明了这种假设可能存在严重错误。通过使用伽马射线扰动角相关法（PAC）测量静态和动态核四极相互作用，分别研究了高度稀释溶质的晶格位置和扩散跳跃频率这两种微观性质。在相反的边界组成下，已观察到 PAC 探针原子占据不同的晶格位置或具有相差 100 倍的跳跃频率。这种粗大差异表明，应在具有相反边界组成的成对样品上进行线化合物其他性质的测量，以避免不一致或不可重现的结果。
Phases having compositional fields narrower than about 1 at.% and appearing as lines in binary phase diagrams often are assumed to have properties independent of composition. That such an assumption can be seriously in error is illustrated by recent measurements on pairs of samples prepared to have compositions at opposing phase boundaries. Two microscopic properties, lattice locations of highly dilute solutes and diffusional jump frequencies, were studied, respectively, through measurement of static and dynamic nuclear quadrupole interactions using the method of perturbed angular correlation of gamma rays (PAC). At opposing boundary compositions, PAC probe atoms have been observed to occupy different lattice sites or to have jump frequencies differing by a factor of 100. Such gross differences suggest measurements of other properties of line compounds should be made on pairs of samples having the opposing boundary compositions in order to avoid inconsistent or unreproducible results.