Extended superstructures in electron-deficient Zintl-type liquid alloys

Zintl phases can be distinguished in the so-called Zintl-Klemm compounds and the electron-deficient compounds. In the covalent bonds of the latter an electron may be shared by more than two atoms. Electron-deficient compounds are found among the alkali-group-13 alloys. The bonding type is reflected in the physical properties and in the structure of the molten alloys. This is demonstrated by a discussion of the alkali-Tl alloys. Finally, new results on liquid alkali-Ga systems are presented. The electron-deficient alloys can form very large clusters (approximate to30 atoms); their structures appear to be ill-defined. (C) 2002 Elsevier Science B.V. All rights reserved.