Jacques Rivet

Etude des proprietes electriques des phases: Cu2GeS3, Cu2SnS3, Cu8GeS6 et Cu4SnS4

Abstract Single crystals of copper tetrahedral ternary compounds have been prepared. Their identity was controlled by X-Ray and density analysis. Electrical properties have been investigated by measurements of their resistivity and Hall constant in the temperature range 77 to 400°K. All the four compounds show semiconducting behaviour.

Study of the Ag-In-Te ternary system. II. Description of the quadrilateral Ag-Ag2Te-In2Te3-In

Abstract The phase diagram of the Ag–Ag 2 Te–In 2 Te 3 –In system was studied by DTA, DSC, XRD, metallography and electron microprobe methods. With the exception of the three known compounds, AgInTe 2 , AgIn 5 Te 8 and Ag 3 In 97 Te 147 that are localized in the Ag 2 Te–In 2 Te 3 quasi-binary section, no other ternary compounds are identified. The eutectic valleys are drawn, and the nature and the location of the ternary invariants are given. Twelve ternary invariants are found: three eutectic points, eight transitory peritectic points and one metatectic point. One ternary liquid–liquid miscibility gap is identified: it originates from the Ag–Ag 2 Te system and overlaps a large region of the Ag–Ag 2 Te–InTe–In system; it is crossed by a eutectic valley, giving a first-class ternary monotectic equilibrium. No glassy region is observed.

Description of the Cu-As-Se ternary system

Abstract The phase diagram of the Cu-As-Se ternary system was studied by differential thermal analysis, X-ray diffraction and metallography analysis. Two ternary phases are observed: the Cu 3 AsSe 4 compound, which melts congruently, and the CuAsSe 2 compound, which undergoes a peritectic decomposition. The ternary system is subdivided into 12 secondary triangles. The 12 ternary invariants are localized: six eutectics, one of which is degenerated at the selenium apex, and six peritectics. Two ternary liquid-liquid miscibility gaps originating from the Cu-Se binary system are identified. One of these is crossed by a eutectic valley giving a first-class ternary monotectic equilibrium. A large vitreous region, which comes from the As-Se binary glass zone, is identified; it overlaps the liquid-liquid miscibility area, giving phase-separated glasses.

Systeme Ag2TeGa2Te3. phases intermediaires. determinations structurales. diagramme de phase

New description of the phase diagram Ag2TeGa2Te3. Three solid solutions are present: in the neighbouring of Ga2Te3, the first one has the sphalerite type from 390°C–450°C to 748–767°C and n = 0 to n = 0.225. Three new surstructures are present below this solid solution respectively for the compositions: n = 0.166 (AgGa5Te8), n ⋍ 0.10 and n ⋍ 0.025. The second solid solution is included between n = 0.36 and n = 0.41. The crystal structure of a term of this solid solution is described. The third solid solution is localized around AgGaTe2. Another compound Ag9GaTe6 has a congruent melting at 710°C and a polymorphic transformation at 29°C. Its crystal structure is in progress. Two eutectics are present for n = 0.75 at 650°C and n = 0.975 at 625°C (n = AgAg+Ga).

Etude du systeme AgIBiI3

Abstract The pseudo-binary system AgI-BiI 3 has been studied by differential thermal analysis (DTA) and by microcalorimetry. An eutectic point was found at 389°C for the composition BiI 3 : 85 mol.BiI 3 p.cent. Two new solid solutions have been discovered. Their existence has been confirmed by X-ray diffraction.

The As-Te system: phase diagram and glass separation

Abstract The As 2 Te 3 compound is usually described as showing non-congruent melting, or congruent melting at a temperature which cannot be differentiated from that of the next eutectic. The As-Te system is here presented using an isochoric diagram, and the specific volume variable is taken into account to explain this anomalous melting. From analyses by electron microprobe of quenched liquid and vapour phases, it may be assumed that the melting of As 2 Te 3 is non-congruent. Vitreous materials are obtained from quenching of the liquid in two zones adjacent to As 2 Te 3 , and from fast quenching of liquid As 2 Te 3 . When glassy products containing 55–80 mol% of As are annealed at temperatures lower than that of the liquidus, separation of a large vitreous phase occurs.

Description du système ternaire CuSnTe

The CuSnTe ternary system has been established by DTA, crystallographic analysis and metallographic analysis. The existence of a ternary compound Cu2SnTe3 is demonstrated; this has a ternary incongruent melting point at 412°C. The four-phase reaction is: This ternary compound has a superstructure of a zinc blende type. This study shows the existence of three ternary eutectics. Two liquid-liquid miscibility gaps exist; the first gives a monotectic reaction within the ternary system while the second corresponds to true liquid immiscibility.

Description du système ternaire AgSbSe

Abstract The phase diagram of the AgSbSe system was studied by differential thermal analysis, X-ray diffraction and metallography analysis. Two ternary phases were observed: the AgSbSe 2 compound, an f.c.c. NaCl-like structure with congruent melting and a new phase, to which the formula Ag 3 Sb 7 Se 12 is attributed. This last compound is dimorphic and the transition between the two forms occurs at about 200 °C. The high temperature structure disappears at about 360 °C. Four quasi-binary sections are described in this ternary system. Seven ternary invariants are characterized: five eutectics of which two are degenerated at the selenium apex, and two peritectics. In the temperature range between 360 and 558 °C, besides the seven three-phase domains, there are five two-phase domains. Three ternary liquid-liquid miscibility gaps are observed, of which only two are crossed by a valley. Finally, a glass domain with a small extension, which comes from a binary glass zone rich in selenium of the SbSe system, was established within the (AgSbSe 2 )SeSb 2 Se 3 triangle.