Abstract: A process for manufacturing a device comprising at least a support and a component, joined together by at least one braze, includes a brazing operation which is carried out starting from a metal oxalate. Advantageously, it is a silver oxalate or a mixture of silver and copper oxalates, the component and/or the support being covered with a film comprising gold or copper in contact with said braze and the component possibly being a power component.

Abstract: A process for manufacturing a device comprising at least a support and a component, joined together by at least one braze, includes a brazing operation which is carried out starting from a metal oxalate. Advantageously, it is a silver oxalate or a mixture of silver and copper oxalates, the component and/or the support being covered with a film comprising gold or copper in contact with said braze and the component possibly being a power component.

Abstract: Oxides having the spinel structure of .gamma.-Fe.sub.2 O.sub.3 /Fe.sub.3 O.sub.4 type, substituted by trivalent and monovalent metals, or doped with non-spinel derivatives thereof, more particularly iron/aluminum/potassium oxides well suited as dehydrogenation catalysts, e.g., for dehydrogenating ethylbenzene into styrene, are prepared by thermally decomposing mixed iron, aluminum and potassium salts, notably the oxalates thereof, in the presence of air, then reducing the product of thermal decomposition at a temperature of less than 400.degree. C., advantageously in the presence of steam and hydrogen, and optionally oxidizing the product of reduction; oxides of .beta.-alumina structure are also produced.

Abstract: Particulate magnetic oxide compositions based on iron oxide (III) and oxide of at least one bivalent metal selected among cobalt, iron, copper, zinc, magnesium, nickel, manganese and cadmium, characterized in that said compositions contain additionally in the form of an oxide from 0.2 to 5% by weight calculated on the total weight at least one additive or substituent selected among alkali metals, alkaline-earth metals, boron, the elements of columns 3, 4 and 5 of the periodical classification of elements having a molecular mass higher than 26, the transition metals 3d and 4d other than those already mentioned, and the rare earths, with the proviso that when an alkali metal or tin is present, at least another additive or substituent is also present, and in that said compositions have a structure of the lanucar spinel type; the preparation and application thereof are also disclosed.