Ternary Gold Hydrides: Routes to Stable and Potentially Superconducting Compounds

Abstract

In a search for gold hydrides, an initial discouraging result of no theor. stability in any binary AuHn at P < 300 GPa was overcome by introducing alkali atoms as reductants. A set of AAuH2 compds., A = Li, Na, K, Rb, and Cs, was examd.; of these, certain K, Rb, and Cs compds. are predicted to be thermodynamically stable. All contain AuH2- mol. units and are semiconducting at P = 1 atm, and some form metallic and superconducting sym. bonded AuHAu sheets under compression. To induce metallicity by bringing the Au atoms closer together under ambient conditions, the authors examd. alk. earth ion substitution for two A, i.e., materials 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 calcd. superconducting transition temps. for these materials. [on SciFinder(R)