title: Hexagonal close-packed structure of au nanocatalysts solidified after ge nanowire vapor-liquid-solid growth.
abstract: We report that approximately 10% of the Au catalysts that crystallize at the tips of Ge nanowires following growth have the close-packed hexagonal crystal structure rather than the equilibrium face-centered-cubic structure. Transmission electron microscopy results using aberration-corrected imaging, and diffraction and compositional analyses, confirm the hexagonal phase in these 40-50 nm particles. Reports of hexagonal close packing in Au, even in nanoparticle form, are rare, and the observations suggest metastable pathways for the crystallization process. These results bring new considerations to the stabilization of the liquid eutectic alloy at low temperatures that allows for vapor-liquid-solid growth of high quality, epitaxial Ge nanowires below the eutectic temperature.
authors.affiliation: Geballe Laboratory for Advanced Materials, Materials Science and Engineering Department, Stanford University, Stanford, California 94305, USA. afm@stanford.edu
authors.forename: Ann F
authors.initials: AF
authors.lastname: Marshall
authors.forename: Irene A
authors.initials: IA
authors.lastname: Goldthorpe
authors.forename: Hemant
authors.initials: H
authors.lastname: Adhikari
authors.forename: Makoto
authors.initials: M
authors.lastname: Koto
authors.forename: Young-Chung
authors.initials: YC
authors.lastname: Wang
authors.forename: Lianfeng
authors.initials: L
authors.lastname: Fu
authors.forename: Eva
authors.initials: E
authors.lastname: Olsson
authors.forename: Paul C
authors.initials: PC
authors.lastname: McIntyre