SEMINARIS DE LA FACULTAT DE GEOLOGIA I L'INSTITUT DE CIÈNCIES DE LA TERRA 'JAUME ALMERA'
Alain MARBEUF
(Laboratoire Optique et Matière d'Aquitaine, Université Bordeaux I - CNRS, França)

As for intermetallic or inorganic alloys, binary molecular alloys are known to crystallize in one of two manners: i) substitutional mixed alloys where molecules of the two types are randomly or short-range ordered in the lattice; ii) complexes with well defined stoechiometry. We will show that the Borelius-Gorsky-Bragg-Williams model, which takes into account medium-range molecular interactions (van der Waals forces, hydrogen bonding) and long-range ones (electrostatic forces), can explain such a behavior. The lattice choice between random and ordered distribution appears as the consequence of the balance between these two kinds of interactions, as shown in some simple cases: alkanes, benzenic or naphthalenic compounds. From a thermodynamic point of view, melts in equilibrium with theses solid phases may reflect partly the lattice ordering, in particular with their mixing functions and with the liquidus shape.

Dia: 23 de novembre de 2011
Lloc: Sala d'actes de l'Institut Jaume Almera
Hora: 12 h