Au-Sn金属间化合物的第一性原理研究

采用基于密度泛函理论的第一性原理平面波赝势法，计算研究了Au-Sn二元系金属间化合物的生成焓、结合能、电子结构、弹性性质和结构稳定性. 计算结果表明：Au₅Sn合金的生成焓最小，说明Au₅Sn较容易生成，但Au₅Sn在热力学和力学上是不稳定的；AuSn₂和AuSn₄的键合作用较强，弹性模量、剪切模量均大于AuSn和Au₅Sn；从电子结构的角度，AuSn₂和AuSn₄ 的成键主要来自于Au原子d 轨道与Sn原子p轨道的杂化；而AuSn以Sn–Sn键的相互作用为主，Au₅Sn相中Au 的占比较大，导致Au–Au共价键发挥作用，抑制了Sn导带p电子的成键. 关键词： 电子结构 弹性性质 第一性原理 Au-Sn金属间化合物

First principles study of Au-Sn intermetallic compounds

A first-principles plane-wave pseudopotential method based on the density functional theory is used to investigate the energies, electronic structures, and elastic properties of intermetallic compounds of Au-Sn system. The enthalpies of formation, the cohesive energies, and elastic constants of these compounds are estimated from the electronic structure calculations, and their structural stabilities are also analyzed. The results show that the Au₅Sn compound is unstable with respect to other compounds, and the bonding effects of AuSn₂ and AuSn₄ are stronger than those of AuSn and Au₅Sn, for there are the strong hybridizations between Au and Sn atoms in AuSn₂ and AuSn₄ compounds. The main bonding effect of AuSn is Sn–Sn bonding interaction, and due to the Au content being maximal in Au₅Sn the bonding of p electrons in Sn conduction band is suppressed by the covalent bonding of Au–Au.
Keywords： electronic structure elastic properties first-principles calculations Au-Sn intermetallic