The research team led by Professor Hu PingAn from School of Materials Science and Engineering at Harbin Institute of Technology has made important progress in the preparation of large-size single-crystal metal foils with high-index facets. The relevant results were published in the journal of Advanced Materials under the title Prestrain Guided Yield of Large Single-Crystal Nickel Foils with High-Index Facets.
The preparation of single-crystal metal foils with high-index facets has important scientific significance and great application potential in fundamental research. The abundant arrangement characteristics of atoms on high-index facets, including stepped and kinked facets, enable them with a highly unsaturated coordination environment. This feature confers strong epitaxial action for the growth of high-quality van der Waals film materials and electrochemical reduction capacity. For example, the step edges of the high-index surface facilitate the continuous epitaxial growth of single-crystal graphite film on single-crystal high-index nickel foils. Additionally, single-crystal films and unidirectional nanoribbons of transition metal dichalcogenides can be grown on low-symmetry vicinal facets with varying Miller indices. However, the controllable synthesis of large single-crystal metal foils with high-index facets remains a great challenge because high-index facets with high surface energy are not preferentially formed thermodynamically and kinetically.
To address this problem, the research team led by Professor Hu PingAn proposed a cold forming prestrain engineering technology for the controllable production of single-crystal nickel foils with high-index facets, with the largest one exceeds 5×8 cm2 in size. The strain energy serves as the driving force to facilitate abnormal grain growth. By adjusting the prestrain, large single-crystal nickel foils with diverse high-index facets can be obtained. The thermodynamic analysis of the internal mechanism underlying the formation of high-index facets through prestrain regulation is conducted. Molecular dynamics simulation is employed to explain and replicate the phenomenon of multiple crystallographic orientations resulting from prestrain regulation. Furthermore, high-quality graphite films were prepared on the single-crystal Ni(012) foils, and the graphite/single-crystal Ni(012) foil composites exhibit exceptional thermal conductivity. This study hence presents a novel approach for the preparation of single-crystal nickel foils with high-index facets, which is beneficial for the epitaxial growth of certain two-dimensional materials.
Paper Link: https://doi.org/10.1002/adma.202400248
