Abstract: The invention relates to a process for the preparation of a binary initial solvent zone for the crystallization in monocrystal form of a ternary or quaternary compound of given composition and containing Cd and Hg. It consists of choosing on the phase equilibrium diagram of the compound, the Cd and Hg concentration and the temperature which crystallization is to take place. When raised to this temperature, the initial solvent zone is able to dissolve the compound until a solvent zone in thermodynamic equilibrium therewith is obtained and on the basis of which it is possible to bring about crystallization. The composition of the initial solvent zone and the temperature at which it is to be prepared are determined on the diagram.

Abstract: Process for the preparation of a polycrystalline alloy for producing monocrystals by passage in a solvent zone.The compound is completely melted by heating it to a temperature above its melting point and for a time sufficient for the homogenization of the liquid. This is followed by a cooling of the liquid by bringing it to a temperature below the melting point thereof. The sudden rise of the temperature occurring at the end of the superfusion of the liquid is monitored and the mixture then undergoes sudden tempering bringing about the instantaneous solidification of the entity in the form of a homogeneous polycrystalline ingot.

Abstract: Process for producing ternary or quaternary semiconductor compounds, particularly of formula Cd Hg Te or Cd Hg Te Se.It comprises the following stages:forming a homogeneous mixture having a precise composition and corresponding to the compound to be obtained, of Cd Te and Hg Te powders in the case of the ternary compound Cd Hg Te and Cd Te Se and Hg Te or Cd Te and Hg Te Se powders in the case of the quaternary compound Cd Hg Te Se;the mixture is compacted by applying a pressure;the thus compacted mixture undergoes thermal interdiffusion treatment;the recrystallization of the compound in monocrystalline form takes place by a single passage through the solvent zone.

Abstract: A method of preparation of a ternary or quaternary alloy composed of the elements A.sup.1 A.sup.2 A.sup.3 (ternary alloy) or the elements A.sup.1 A.sup.2 A.sup.3 A.sup.4 (quaternary alloy) consists of the successive steps of preparation of one or a number of binary alloys such as A.sup.1 A.sup.2, purification of the binary alloys by zone melting, placing of the binary alloy or alloys which are in the solid state together with the other constituent elements of the alloy within a container in the presence of a solvent, crystallization of the ternary or quaternary alloy by melting all the elements within the container and recrystallization in the presence of the solvent.