Formation of an Intermediate Valence Icosahedral Quasicrystal in the Au-Sn-Yb System

Tsunetomo Yamada; Yoko Nakamura; Tetsu Watanuki; Akihiko Machida; Masaichiro Mizumaki; Kiyofumi Nitta; Akira Sato; Yoshitaka Matsushita; An-Pang Tsai

doi:10.1021/acs.inorgchem.9b00801

Formation of an Intermediate Valence Icosahedral Quasicrystal in the Au-Sn-Yb System

Inorg Chem. 2019 Jul 15;58(14):9181-9186. doi: 10.1021/acs.inorgchem.9b00801. Epub 2019 Jun 25.

Authors

Tsunetomo Yamada¹, Yoko Nakamura², Tetsu Watanuki³, Akihiko Machida³, Masaichiro Mizumaki⁴, Kiyofumi Nitta⁴, Akira Sato⁵, Yoshitaka Matsushita⁵, An-Pang Tsai²

Affiliations

¹ Department of Applied Physics, Faculty of Science , Tokyo University of Science , 6-3-1, Niijuku , Katsushika-ku, Tokyo 125-8585 , Japan.
² Institute of Multidisciplinary Research for Advanced Materials , Tohoku University , 2-1-1 Katahira, Aoba-ku , Sendai , Miyagi 980-8577 , Japan.
³ Synchrotron Radiation Research Center , National Institutes for Quantum and Radiological Science and Technology , 1-1-1 Kouto , Sayo , Hyogo 679-5148 , Japan.
⁴ Japan Synchrotron Radiation Research Institute (JASRI) , 1-1-1 Kouto , Sayo , Hyogo 679-5198 , Japan.
⁵ Research Network and Facility Services Division , National Institute for Materials Science (NIMS) , 1-1 Namiki , Tsukuba , Ibaraki 305-0044 , Japan.

PMID: 31247815
DOI: 10.1021/acs.inorgchem.9b00801

Abstract

We report on the formation of a new icosahedral quasicrystal (iQC) in the Au-Sn-Yb alloy system. This iQC has a primitive icosahedral lattice with a lattice constant a_ico of 0.5447(7) nm and a composition that was determined to be Au_60.0Sn_26.7Yb_13.3. X-ray absorption spectroscopy measurement of the near Yb L₃ edge demonstrates that the Yb valence in the iQC is an intermediate valence between divalent (4f¹⁴) and trivalent (4f¹³) at ambient pressure and was determined to be 2.18+. The results are compared to those for a corresponding 2/1 cubic approximant crystal. The formation of this new iQC is discussed in terms of the atomic size factor (δ) and the valence electron-to-atom ratio (e/a).