Large Single‐Crystal Cu Foils with High‐Index Facets by Strain‐Engineered Anomalous Grain Growth

• Published in: Advanced materials (Weinheim) Vol. 32; no. 29; pp. e2002034 - n/a
• Main Authors: Li, Yanglizhi, Sun, Luzhao, Chang, Zhenghua, Liu, Haiyang, Wang, Yuechen, Liang, Yu, Chen, Buhang, Ding, Qingjie, Zhao, Zhenyong, Wang, Ruoyu, Wei, Yujie, Peng, Hailin, Lin, Li, Liu, Zhongfan
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01-07-2020
• Subjects: anomalous grain growth; Chemical properties; Contact stresses; Coordination compounds; Cu foils; Epitaxial growth; Grain growth; high‐index facets; Materials science; Metal foils; Single crystals; strain‐engineering; Surface energy; Thermal strain; Two dimensional materials
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.202002034

The rich and complex arrangements of metal atoms in high‐index metal facets afford appealing physical and chemical properties, which attracts extensive research interest in material science for the applications in catalysis and surface chemistry. However, it is still a challenge to prepare large‐area high‐index single crystals in a controllable and cost‐efficient manner. Herein, entire commercially available decimeter‐sized polycrystalline Cu foils are successfully transformed into single crystals with a series of high‐index facets, relying on a strain‐engineered anomalous grain growth technique. The introduction of a moderate thermal‐contact stress upon the Cu foil during the annealing leads to the formation of high‐index grains dominated by the thermal strain of the Cu foils, rather than the (111) surface driven by the surface energy. Besides, the designed static gradient of the temperature enables the as‐formed high‐index grain seed to expand throughout the entire Cu foil. The as‐received high‐index Cu foils can serve as the templates for producing high‐index single‐crystal Cu‐based alloys. This work provides an appealing material basis for the epitaxial growth of 2D materials, and the applications that require the unique surface structures of high‐index metal foils and their alloys.
Large single‐crystal Cu foils with high‐index facets are successfully achieved by using strain‐engineered anomalous grain growth, in which a graphite susceptor provides moderate strain on the Cu foil. The minimization of the strain energy leads to the formation of anomalous Cu grains with high‐index facets, which is investigated by the theoretical calculations.