Icosahedral quasicrystal, 1/1 and 2/1 approximants in Zn-based ternary alloys containing Au and Yb/Tb

ABSTRACT

In a narrow composition range centred at Zn_74.5Au_10.5Yb_15.0, Tsai-type icosahedral quasicrystal is formed in alloys quenched from 880°C. This quasicrystal belongs to the primitive type with the 6-dimensional lattice parameter a_6D= 7.378 Å. The quasicrystal was not formed in the slowly cooled specimen, and was considered a metastable phase. The stable phase is a 2/1 approximant of the lattice parameter a_2/1 = 23.271 Å. This approximant forms exclusively in Zn_76.0Au_9.0Yb_15.0 alloy annealed at 530°C. In addition, Zn_70.5Au_15.5Tb_14.0 alloy annealed at 505°C forms a Tsai-type 1/1 approximant (a_1/1 = 14.343 Å). These new Zn-based phases observed in this study correspond to the quasicrystal-related phases in binary Cd-lanthanoid systems, and show the possibility of isostructural substitution of Cd by Zn/Au.

KEYWORDS:

• Quasicrystals
• icosahedral phases
• approximants
• Tsai-type
• Zn-based alloys

Acknowledgement

The author thanks N.K. Sato. K. Deguchi and K. Imura for valuable discussions through this study. This work was supported by Kakenhi Grant-in-Aid numbers 17K05524 and 19H05818 from the Japan Society for the Promotion of Science (JSPS).

Disclosure statement

No potential conflict of interest was reported by the author.

Additional information

Funding

This work was supported by Kakenhi Grant-in-Aid numbers 17K05524 and 19H05818 from the Japan Society for the Promotion of Science (JSPS).