Local order and phase separation in sulphur-tellurium melts: a neutron scattering study

A neutron scattering investigation of the local order in liquid sulphur-tellurium was performed for alloys at x(s) = 0.2, 0.3, 0.4, 0.6 and 0.8, at three temperatures. A detailed analysis of the structure in terms of partial coordination number is performed by means of a modelling of the structure factors at large momentum-transfer range. Local order changes are essentially caused by tellurium whose coordination number decrease from 2.6 to 1.8 in a 20% composition range. The change in the local atomic environment is shown to be responsible for the observed miscibility gap that occurs around x(s) = 0.4. (C) 1999 Elsevier Science B.V. All rights reserved.