Oxidation of M4Si4 (M = Na, K) to Clathrates by HCl or H2O

This is the authors' abstract. We don't add key points for this paper.

The synthesis of clathrate-II germanium □ 24 Ge 136 in an ionic liquid was recently discovered. 1 The key step in this process, the controlled oxidation of reactive precursor phases by a protic acid, was successfully applied to silicides M 4 Si 4 (M = Na, K). Through this method, clathrate-I compounds of composition M 8- x Si 46 were obtained as crystalline products. The synthetic method demonstrates a mild oxidative route to a large class of metastable intermetallic compounds.