Abstract: A method of preparing faces of a laser based on III-IV compounds, the method comprising the following operations:1) the faces of the laser are opened;2) said faces of the laser are placed in an enclosure in which there obtains a pressure of about 10.sup.-7 mbar to about 10.sup.-8 mbar, and they are subjected to a step of cleaning by irradiation with a pulsed laser; and3) the same pulsed laser is used to ablate a target so as to subject said faces to a passivation operation whereby silicon Si or gallium nitride GaN is deposited thereon by the pulsed laser deposition method until a thickness is obtained lying in the range 2 .ANG. to 20 .ANG..

Abstract: A method of preparing a substrate with a view to depositing a thin layer of a superconductive material thereon, wherein an operation is performed of depositing on the substrate an intermediate material having the property of having a crystal lattice constant that is a function of the percentage of a doping element, the depositing operation being initiated with a concentration of the doping element such that the lattice constant of the intermediate material is equal to or as close as possible to the lattice constant of the substrate, the proportion of the doping element being continuously varied during the depositing operation to a proportion of the doping element such that the lattice constant of the intermediate material is equal to or as close as possible to the lattice constant of the superconductive material.

Abstract: A method of making a solid magnetic material from Sm.sub.2 Fe.sub.17 N.sub.3-x type intermetallic nitride powder, where 0.ltoreq.x.ltoreq.1, comprises the following steps:a--the powder is mixed intimately with glass powder having a conversion temperature Tg between 260.degree. C. and 310.degree. C. and a softening temperature Tf less than 400.degree. C., the proportion of glass powder being between 10% and 30% of the total volume;b--the mixture is compressed to obtain a solid;c--the solid obtained is subjected in a neutral gas atmosphere to a heat cycle during which a temperature not less than Tf+5.degree. C. and not more than 420.degree. C. is maintained for at least one hour.

Abstract: A superconducting current limiter comprising a bar or tube of high temperature superconducting material of the composite type made up of glass and a high temperature superconducting oxide, the volume fraction of the glass lying in the range 10% to 40%, the bar or tube being selected to comply with the following inequalities:.rho.>10.sup.-4 .OMEGA..multidot.mj.sub.c >10.sup.+5 A/m.sup.2.rho.x.sup.2 <10.sup.11 W/m.sup.3in which inequalities:.rho. designates the resistivity of the material in the normal, i.e. the non-superconducting, state;j.sub.c designates the critical current density;.rho.x.sup.2 designates the power density dissipated in the bar or tube during the transition stage;it being specified that the critical current density is defined as the density which produces an electric field of 10.sup.-4 V/m along the tube or bar and that it is accepted that limitation takes place for a current density equal to five times the critical current density.

Abstract: A melting-and-solidification manufacturing method for manufacturing an ingot of a high critical temperature superconductive oxide belonging, in particular, to the YBaCuO, BiSrCaCuO, or TlBaCaCuO families, wherein:an ingot of oxide having the appropriate stoichiometery is used;the ingot is held horizontally by levitation on a film of gas inside a furnace;the ingot is melted;a vertical thermal gradient is established inside said furnace such that nucleation starts at the bottom portion of said ingot;while maintaining said thermal gradient, the overall temperature of the furnace is lowered at a rate of not more than 0.1.degree. C./hour down to the temperature which corresponds to complete ingot solidification; andfinally, conventional oxygenation treatment is applied to said ingot.

Abstract: A method of making a preform for an optical fiber, in which method a plurality of layers of fluoride glass are deposited inside a support tube (10); said layers (14) are deposited by laser ablation in a controlled atmosphere using a target (12) having the composition of said glass, which target is moved back-and-forth parallel to the axis of said tube, the temperature of the enclosure (1) in which said ablation is performed being not greater than the vitreous transition temperature Tg of said glass.

Abstract: A method of manufacturing a component of the tape or filament kind out of a material based on a superconducting oxide having a high critical temperature, wherein said material is formed while it is in the vitreous state,the method being characterized by the fact that the material is subsequently crystallized:in a first step under a magnetic field and at a temperature T.sub.l lying between the vitreous transition temperature T.sub.g and the crystallization temperature T.sub.x, during which step isolated microcrystallites of submicroscopic size develop and their c axes orient themselves parallel to one another because of said applied magnetic field; andin a second step at a temperature T.sub.2 close to the crystallization temperature, in which the existing nuclei grow while retaining the texture imparted to them during said first step.

Abstract: A tape based on a superconducting oxide containing Cu-O, the tape being characterized by the fact that it comprises a substrate of flexible metal or composite material having a rectangular cross-section and provided on at least one of its faces with a cavity-free film of perovskite type superconducting oxide having congruent or quasi-congruent melting or peritectic decomposition close to a eutectic point, the thickness of said film lying in the range 1 .mu.m to 100 .mu.m, the orientation of the C axis of the superconducting crystals being perpendicular to said face of said substrate.

Abstract: The inventive means includes a supply vessel (10) having a bottom opening (14), feed means (15 to 17) for supplying the vessel (10) with solid silicon and means (11 to 13) for heating the vessel, said vessel being placed above the crucible (1) containing the melt (8) so that the molten silicon in the vessel (10) flows out through the bottom opening (14) into the crucible (1) when the level (h) of the molten silicon in the supply vessel reaches a maximum value (20) and the replenishing flow stops when the level (h) has fallen to a minimum value (22). An application involving the deposition of a layer of polycrystalline silicon onto a carbon tape is described.

Abstract: The method consists in clamping the edges of the tape between two jaws of a clamp and in displacing the clamp vertically upwardly. The apparatus includes two vertical columns (10, 11) along which two carriages (12, 13) are capable of moving, with each carriage having a corresponding clamp (14, 15) and means (16, 17, 19, 20) for controlling clamp operation and vertical displacement of the carriages along the columns. Such semiconductor-coated material is suitable for making solar photocells, for example.

Abstract: It comprises a receptacle containing a bath of molten silicon, the bottom of the receptacle includes a slot (7) through which there passes a tape (9) which is drawn vertically through the bath. The vertical wall of the slot (7) is downwardly flared, the horizontal section of the slot (7) includes a rectangular area (25) whose length is equal to the width of the tape (9) and two circular areas (28, 29) disposed at the two ends of the rectangular area (25), the diameter (32) of the circular areas (28, 29) being greater than the width of the rectangular area (25).Application to making solar photocells from silicon.

Abstract: A crucible containing molten silicon, has a strip of carbon film vertically transported through the melt, an optical system imaging a small area of the silicon surface onto a photodetector, said image area being that of the silicon liquid-solid interface, and a servo system connected to said photodetector and to an electrical drive for feeding silicon into said melt. The invention is applicable to the manufacture of solar cells.

Abstract: A device for depositing a layer of polycrystalline silicon on a carbon tape comprises a bath of molten silicon through which the carbon tape is drawn vertically. Two semicircular channels are supported vertically in the vicinity of the edges of the tape with their concave side towards the tape. The channels are partially immersed in the bath so as to raise the level of its surface by capillary action. The device is applicable to the manufacture of solar cells.

Abstract: A fabrication method for use in making photocells consisting in depositing on the top face of a carbon ribbon (4) being moved horizontally in its lengthwise direction through an oven (9) a layer of silicon, said oven being imparted a vertical temperature gradient, and in burning away the portion of the ribbon supporting the silicon layer immediately following deposition of said layer.

Abstract: A method of manufacturing semiconductor devices comprising a layer of semiconductor material, comprising the steps of providing a strip-shaped solid substrate having a main surface and providing a solid support having a substantially horizontal surface and comprising a substantially floating liquid mass of such semiconductor material on the substantially horizontal surface, the main surface being wettable by the liquid semiconductor material. The liquid mass is contacted with the main surface of said substrate, onto which substrate the layer of semiconductor material is to be provided, the substrate is moved in its longitudinal direction along and in contact with said liquid mass so that a liquid layer of said semiconductor material is formed on said strip and taken along with it, and the liquid layer is substantially progressively solidified.

Abstract: A device for stirring a liquid having two cup-shaped elements coaxially mounted on the end of a shaft. Radial vanes extend between the two elements to define liquid flow passages, the liquid entering from a hole at the apex of the outer cup. The outlet end of each of the vanes is bent at approximately a right angle to the rest of the vane.