A Sodium-Containing Quasicrystal: Using Gold To Enhance Sodium’s Covalency in Intermetallic Compounds


  • We are indebted to J. Jacobs for ICP-MS analyses and K. Dennis for DSC measurements. The research was supported by the Office of the Basic Energy Sciences, Materials Sciences Division, U. S. Department of Energy (DOE). Ames Laboratory is operated for DOE by Iowa State University under contract No. DE-AC02-07CH11358. Use of the Advanced Photon Source was supported by the US DOE under Contract No. DE-AC02-06CH11357.


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Golden opportunity: Na13Au12Ga15 is the first Na-containing, thermodynamically stable quasicrystal and was discovered during systematic exploration of the polar intermetallic Na–Au–Ga system. Its electron-to-atom ratio, 1.75, is extremely low for Bergman-type icosahedral phases, but it is the substantial Au content that allows Hume–Rothery stabilization and promotes novel Na–Au polar–covalent interactions, which stabilize the icosahedral phase.