Yves Feutelais

Thermodynamic investigation in In–Sb, Sb–Sn and In–Sb–Sn liquid systems

Abstract Using a molten salt method, EMF measurements have been obtained for In–Sb, Sb–Sn and In–Sb–Sn alloys. New DSC experiments on Sb–Sn system gave a confirmation of the proposed Sb–Sn equilibrium phase diagram. A thermodynamic description of the ternary liquid in fair agreement with the experimental results has been obtained from the geometrical Muggianu approach.

Importance of heat capacity determination in homogeneous nucleation: application to progesterone

Progesterone is known to exist under different crystallographic forms in the solid state. The thermodynamic stable form (I), melts at 129.2 ◦ C (402.35 K) under atmospheric pressure. After melting and cooling a metastable form (II) can be obtained which melts at 122 ◦ C (395.15 K). This uncommon behaviour can be explained with the theory of nucleation, only if heat capacity of the different forms are known.

Engineering a GABA endowed with pharmacological CNS activity when given by an extracerebral route

Gamma-aminobutyric acid (GABA) is a major inhibitory neurotransmitter physiologically active in the central nervous system (CNS), being synthesised and delivered by GABAergic neurons. It is, however, pharmacologically devoid of CNS activity when presented externally to brain because of limited blood–brain barrier diffusion and intensive breakdown by astrocyte GABA transaminase. We show herein that extracerebral administration may be, however, pharmacologically effective in controlling experimental convulsive attacks when GABA is submitted to sublimation under vacuum just before use. Though initially enigmatic because nuclear magnetic resonance (NMR) and infrared (IR) analyses identified the sublimation-derived compound to be the reference zwitterionic GABA, this observation was understood by showing that the reference and sublimated GABAs were monoclinic and tetragonal phases of GABA solid, respectively.

Standard enthalpy of formation of the ζ-phase in the Fe-Zn system at 298 K

Abstract The standard enthalpy of formation Δ f H m(298) of the ζ-phase with composition Fe 0.07 Zn 0.93 was determined using a Tian-Calvet calorimeter (Setaram) by dissolution in an aluminium bath at 801 °C (1074 K). The alloy was prepared by direct melting followed by annealing. The experimental value found was Δ f H m(298) =−2178±772 J/mol.

Standard enthalpy of formation of Al0.28Fe0.72 at 298 K

Abstract The standard enthalpy of formation ΔfHm,(298) for the compound Al0.28Fe0.72 has been determined with a Tian-Calvet calorimeter (Setaram), by dissolution in an aluminium bath at 800°C (1073 K). The single-phase alloy was prepared by levitation melting followed by annealing. The experimental value found is ΔfHm,(298)=−24 645±422 J/mol.

Enthalpy of formation of the ternary τ′ phase in the Al–Cu–Zn system

Abstract Thermodynamic databases and targeted thermodynamic experiments, which validate the calculations and/or provide extra information, may be used together to obtain proper phase diagrams. In the case of the Al–Cu–Zn system, thermodynamic data on the ternary phase is missing for a complete optimisation of the system. In this paper the heat of formation at 298 K of a ternary alloy with a composition and structure corresponding to the ternary τ′ phase is calculated from calorimetric measurements. These values have been obtained with a Tian–Calvet calorimeter, by dissolution in an aluminium bath at 976 K.