E. Dichi

Experimental equilibrium phase diagram of the Ag–Bi–Sn system

Abstract The equilibrium phase diagram of Ag–Bi–Sn ternary system was studied by X-ray powder diffraction analysis, differential scanning calorimetry and differential thermal analysis. Three isopletic sections were studied: 10 at.% Bi, 40 at.% Ag and 70 at.% Bi. Three transitory invariant reactions were characterized: two ternary transitory peritectics and one ternary eutectic. Moreover, from all equilibrium temperatures we were able to propose a description of ternary liquidus surface in the whole composition range.

Study of the ternary system germanium–antimony–tin: experimental phase diagram☆

Abstract The phase diagram of the ternary system Ge–Sb–Sn was established by X-ray powder diffraction and differential scanning calorimetry. No ternary compound was found. Two vertical sections were studied in order to follow the reaction path. Four ternary reactions were characterised: three transition peritectic (U-type) reactions and one eutectoid (E-type) reaction. Moreover, from all equilibrium temperatures, a description of liquidus surface in the whole composition range is proposed.

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.

Système ternaire thallium-étain-tellure I. Triangulation du système ternaire thallium-étain-tellure et étude des coupes isoplèthes SnTe-TlTe et Te-Tl2SnTe3

Abstract The triangulation of the ternary system thallium-tin-tellurium and the phase diagrams of vertical sections SnTe-TlTe and Te-Tl 2 SnTe 3 were established by X-ray powder diffraction, differential thermal analysis and differential scanning calorimetry. The ternary room temperature section contains twelve three-phase regions with five binary phases SnTe, Tl 2 Te 3 , TlTe, Tl 5 Te 3 , γ and three ternary phases Tl 2 SnTe 5 , Tl 2 SnTe 3 and Tl 4 SnTe 3 . The phase diagrams of the vertical sections SnTe-TlTe and Te-Tl 2 SnTe 3 show that the compound Tl 2 SnTe 3 is formed at 364 °C by a binary peritectic reaction of the type p while Tl 2 SnTe 5 is formed at 286 °C by a ternary peritectic reaction of the type P. The phase Tl 4 SnTe 3 has a congruent melting point at 548 °C.

Système ternaire thallium-étain-tellure II. Etude des coupes isoplèthes SnTeTl4SnTe3 et Tl4SnTe3Tl5Te3

Abstract The thallium-tin-tellurium ternary system can be divided into two independent regions by the vertical sections SnTe-Tl 4 SnTe 3 and Tl 4 SnTe 3 -Tl 5 Te 3 which can be regarded as pseudo-binaries. The SnTe-Tl 4 SnTe 3 and Tl 4 SnTe 3 -Tl 5 Te 3 phase diagrams have been established by X-ray powder diffraction, differential thermal analysis and differential scanning calorimetry. The SnTe-Tl 4 SnTe 3 phase diagram, which we give, agrees with the literature. However, we disagree with bibliography results concerning the Tl 4 SnTe 3 -Tl 5 Te 3 vertical section which is regarded as an unlimited solid solution. A study in the region near Tl 5 Te 3 shows a eutectic and two solid solutions regions: 〈Tl 4 SnTe 3 〉 and 〈Tl 5 Te 3 〉.

Système ternaire thallium-étain-tellure IV. Etude du pentagone SnTeSnTl-Tl5Te3Tl4SnTe3

Abstract The pentagon SnTeSnTlTl 5 Te 3 Tl 4 SnTe 3 was studied by X-ray powder diffraction, differential thermal analysis, differential scanning calorimetry, electron microprobe microscopy and metallographic analysis. A large liquid-liquid miscibility gap overlaps the pentagon and is situated above the binary liquid-liquid miscibility gap. Seven ternary invariants were determined, of which five correspond to the five secondary triangles and two to the two monotectic triangles.

Study of the ternary system cadmium-germanium-tellurium: phase equilibria in the ternary system

Abstract The ternary system CdGeTe has been studied by differential thermal analysis, differential scanning calorimetry and X-ray powder diffraction analysis. No definite ternary compound has been found. Two isoplethic sections are quasi-binaries. So, the ternary system is divided in three subternaries. The establishment of the ternary phase diagram of four isoplethic sections has made it possible to determine the layout of the eutectic and peritectic valleys and thus to delimit the different primary crystallization areas. Four ternary invariants have been determined, two of which are ternary eutectics and one is a peritectic ternary corresponding to the three subternaries and a ternary metatectic invariant.

Système ternaire thallium-étain-tellure III. Etude du quadrilatère SnTeTl4SnTe3Tl5Te3Te

Abstract The phase diagram of the quadrangle SnTeTl4SnTe3Tl5Te3Te was established by X-ray powder diffraction, differential thermal analysis and differential scanning calorimetry. Phase diagram interpretation of 11 vertical sections has enabled us to determine the crystallization sheets and various ternary equilibria. The compositions and temperatures of eight ternary invariants have been given.

Study of the ternary phase diagrams of the cadmium–germanium–tin and cadmium–germanium–lead systems

Abstract The ternary systems Cd–Ge–Sn and Cd–Ge–Pb were investigated using thermal analysis (D.T.A. and D.S.C.), X-ray diffraction on powders and metallography. No ternary compound was found. Eight sections were studied (three in the Cd–Ge–Sn ternary system and five in the Cd–Ge–Pb ternary system) in order to follow the reaction path for any composition of these two ternary systems. Analysis of the polythermal projection of these systems are given.