Local order in liquid potassium-antimony alloys studied by neutron scattering and ab initio molecular dynamics

¹ Centre de Thermodynamique et de Microcalorimetrie (UP CNRS 7461), 26, rue du 141ème RIA, F-13331 Marseille, France
² Institut für Theoretische Physik and Center for Computational Material Science, Technische Universität Wien - Wiedner Hauptstraße 8/10, A-1040 Wien, Austria
³ Laboratoire Léon Brillouin (CEA-CNRS), CE Saclay, F-91191 Saclay, France

Received: 8 June 1998
Accepted: 13 July 1998

Abstract

The structure and chemical bonding properties of liquid K-Sb alloys have been investigated using neutron scattering experiments and ab initio molecular-dynamics simulations. For alloys containing between 25 and 50 at. % Sb, the neutron data demonstrate the existence of a well-defined prepeak at reflecting a pronounced short-range order. The ab initio calculations show that the chemical bonding obeys a generalized Zintl principle, i.e. a formally complete electron transfer from K to Sb. The liquid structure is determined for the “octet” composition by charge ordering effects leading to a salt-like atomic arrangement, at the equiatomic composition by the formation of short covalently bonded Sb chains in close analogy to the isoelectronic chalcogen elements in the liquid state.