ja7b04456_si_001.pdf (7.25 MB)
Ternary Gold Hydrides: Routes to Stable and Potentially Superconducting Compounds
journal contribution
posted on 2017-06-19, 04:31 authored by Martin Rahm, Roald Hoffmann, N. W. AshcroftIn a search for gold hydrides, an
initial discouraging result of
no theoretical stability in any binary AuHn at P < 300 GPa was overcome by introducing alkali
atoms as reductants. A set of AAuH2 compounds, A = Li,
Na, K, Rb, and Cs, is examined; of these, certain K, Rb, and Cs compounds
are predicted to be thermodynamically stable. All contain AuH2– molecular units and are semiconducting
at P = 1 atm, and some form metallic and superconducting
symmetrically bonded AuHAu sheets under compression. To induce metallicity
by bringing the Au atoms closer together under ambient conditions,
we examined alkaline earth ion substitution for two A, i.e., materials
of composition AE(AuH2)2. For AE = Ba and Sr,
the materials are already marginally metallic at P = 1 atm and the combination of high and low phonon frequencies and
good electron–phonon coupling leads to reasonably high calculated
superconducting transition temperatures for these materials.