title: Formation of Hexagonal-Close Packed (HCP) Rhodium as a Size Effect.
abstract: Previous studies on the structural and functional properties of rhodium are based on the face-centered-cubic (fcc) structure in the bulk form. Here we report the first discovery of the hexagonal-close packed (hcp) rhodium in the nanoparticle form. The hcp Rh can be directly synthesized by solvothermal reaction or by electron-beam induced decomposition of Rh monolayers. The hcp Rh nanoparticles are stable under electron beam irradiation. Compared with the fcc structure, the hcp Rh nanoparticles show a large lattice expansion (6% larger atomic volume). The first-principles calculations suggest that the lower surface energy of hcp Rh leads to the size effect in the crystal structure.
authors.affiliation: National Center for Electron Microscopy in Beijing, School of Materials Science and Engineering, Key Laboratory of Advanced Materials of Ministry of Education of China, State Key Laboratory of New Ceramics and Fine Processing, Tsinghua University , Beijing 100084, China.
authors.forename: Jing Lu
authors.initials: JL
authors.lastname: Huang
authors.affiliation: Department of Chemistry, Tsinghua University , Beijing 100084, China.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Li
authors.affiliation: Department of Chemistry, Tsinghua University , Beijing 100084, China.
authors.forename: Hao Hong
authors.initials: HH
authors.lastname: Duan
authors.affiliation: National Center for Electron Microscopy in Beijing, School of Materials Science and Engineering, Key Laboratory of Advanced Materials of Ministry of Education of China, State Key Laboratory of New Ceramics and Fine Processing, Tsinghua University , Beijing 100084, China.
authors.forename: Zhi Ying
authors.initials: ZY
authors.lastname: Cheng
authors.forename: Ya Dong
authors.initials: YD
authors.lastname: Li
authors.affiliation: National Center for Electron Microscopy in Beijing, School of Materials Science and Engineering, Key Laboratory of Advanced Materials of Ministry of Education of China, State Key Laboratory of New Ceramics and Fine Processing, Tsinghua University , Beijing 100084, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhu
authors.affiliation: National Center for Electron Microscopy in Beijing, School of Materials Science and Engineering, Key Laboratory of Advanced Materials of Ministry of Education of China, State Key Laboratory of New Ceramics and Fine Processing, Tsinghua University , Beijing 100084, China.
authors.forename: Rong
authors.identifier: 0000-0003-1687-3597
authors.initials: R
authors.lastname: Yu