Ferrando Riccardo
Dipartimento di Fisica and CNR/IMEM, Università degli Studi di Genova, Via Dodecaneso 33, 16146, Genova, Italy.
J Phys Condens Matter. 2015 Jan 14;27(1):013003. doi: 10.1088/0953-8984/27/1/013003. Epub 2014 Dec 8.
Nanoalloys are bi- or multi-component metallic particles in the size range between 1 and 100 nm. Nanoalloys present a wide variety of structures and properties, which make them suitable for many applications in catalysis, optics, magnetism and biomedicine. This topical review is devoted to the structural properties of nanoalloys of weakly miscible metals, which are expected to present phase-separated arrangements of their components, such as core-shell and Janus arrangements. The focus is on singling out size- and composition-dependent transitions between these arrangements, showing that several transitions can be rationalized by a unifying concept, that is symmetry breaking, caused by the accumulation of strain at the atomic level and its subsequent release. The driving forces that rule the interplay between core-shell and other structures and determine the actual shapes of core and shell, and the placement of the core inside the shell are analyzed. Several systems, such as Ag-Cu, Ag-Co, Ag-Ni, Au-Co, Au-Pt, and Ir-Pt are treated, comparing computational results to experimental observations and simple analytical models. After treating the lowest-energy structures, which are representative of the equilibrium configurations at sufficiently low temperatures, high-temperature and growth kinetics effects are considered.
纳米合金是尺寸在1至100纳米之间的二元或多组分金属颗粒。纳米合金具有各种各样的结构和性能，这使其适用于催化、光学、磁性和生物医学等许多应用领域。本专题综述致力于研究弱互溶金属纳米合金的结构特性，这类合金预计会呈现其组分的相分离排列，如核壳结构和两面神结构。重点在于找出这些排列之间尺寸和成分依赖的转变，表明几种转变可以通过一个统一的概念来合理化解释，即由原子水平上应变的积累及其随后的释放所导致的对称性破缺。分析了支配核壳结构与其他结构之间相互作用并决定核与壳实际形状以及核在壳内位置的驱动力。研究了几个体系，如银 - 铜、银 -钴、银 -镍、金 -钴、金 -铂和铱 -铂体系，将计算结果与实验观察结果以及简单的分析模型进行了比较。在研究了代表足够低温下平衡构型的最低能量结构之后，还考虑了高温和生长动力学效应。
