STRUCTURE IN LIQUID KTL INVESTIGATED BY MEANS OF NEUTRON-DIFFRACTION USING TL-205 ISOTOPE SUBSTITUTION

In recent neutron diffraction measurements on liquid KTl, a prepeak wa s observed in the structure factor at a rather low value of the wave v ector of 8 nm(-1). It corresponds to a periodicity in real space of 0. 93 nm. In solid KTl and K8Tl11, Tl clusters of, respectively, 6 and 11 atoms occur. It was concluded that parts of these clusters survive in the liquid state. In order to obtain more information on the structur e of the clusters, we have performed an additional neutron diffraction experiment on D4 (ILL, Grenoble France) using Tl-205 isotope substitu tion. From the additional data it is concluded that the prepeak occurs only in the Tl-Tl partial structure factor. Using RMC modelling of th e isotopic data we are able to determine partial structure factors. Th e average Tl-Tl coordination number is 3.0 +/- 0.1. (C) 1998 Elsevier Science B.V. All rights reserved.