Abstract: Monophase crystalline mixed borates having the formula: M(II).sub.1-x Eu(II).sub.x M(III).sub.p Eu(III).sub.q Tb(III).sub.r B.sub.9 O.sub.16 wherein M(II) is at least one bivalent metal selected among barium, strontium, lead and calcium, it being understood that, in a given mixed borate, the lead and the calcium, together represent not more than 20% by moles based on the total number of moles of metals M(II); M(III) is a metal selected among lanthanum, gadolinium, yttrium, serium, lutetium and bismuth; x is a number higher or equal to zero and smaller than or equal to 0.2; p, q and r is different from zero; and the sum p+q+r equals 1; preparation method and luminescent composition containing them.

Abstract: A refractory fibrous preform in ceramic material is placed inside an infiltration chamber where it is heated within a reacting gaseous mixture introduced into the chamber and containing at least one gaseous hydrolyzing or oxidizing agent and a volatile hydrolyzable or oxidizable compound of the one element or of each element of which the oxide is a constituent of the matrix of the structure to be produced, in order to obtain by chemical reaction an adhesive deposit of said oxide or oxide constituting said matrix and having a melting point higher than 1750.degree. C.

Abstract: There is provided an efficient method of storing hydrogen in materials of small mass and small volume. The products of the present invention comprise intimate mixtures (as opposed to alloys) of magnesium and other metals or alloys capable of forming hydrides. The hydrides are selected so that the hydrides have a substantially lower thermal stability than that of magnesium hydride.

Abstract: Process for making a novel ferromagnetic chromium dioxide and rhodium dioxide material in the form of a solid solution Cr.sub.1-x Rh.sub.x O.sub.2 where x is a number between 0 and 0.5.It essentially comprises oxidation, under suitable conditions of temperature and pressure, of hydrated or anhydrous Cr.sub.2 O.sub.3 or of a precursor of Cr.sub.2 O.sub.3, in the presence of (1) an appropriate amount of a compound of rhodium III able to give RhO.sub.2 under reaction conditions and (2) of an oxidizing agent consisting of an oxygenated compound free from metallic cations other than chromium and having, under the reaction conditions, a partial oxygen pressure at least equal to that corresponding, under the same conditions of temperature and pressure, to the equilibria Cr.sub.2 O.sub.3 +1/2O.sub.2 .revreaction.2CrO.sub.2 and Rh.sub.2 O.sub.3 +1/2O.sub.2 .revreaction.2RhO.sub.

Abstract: The invention relates to the storing of hydrogen in hydrides of metallic alloys.These alloys include besides magnesium an element chosen from the lanthanides and/or element of group IIa of the periodic classification of elements. The magnesium may be, furthermore, possibly substituted among others by a transition metal. These alloys allow the reactivity of the magnesium to be increased in relation to the hydrogen during the hydrogen absorption process as shown by the curves of FIG. 1.Application: supplying hydrogen engines or other hydrogen energy receiving or transforming means with hydrogen.

Abstract: An amorphous cationic conductor of lithium comprising a composition corresponding to the general formula:{B.sub.2 O.sub.3, xM, yN} , aLi.sub.2 O, bLi.sub.z Q 11in which:M is chosen from the group formed by:Al.sub.2 O.sub.3, V.sub.2 O.sub.5, P.sub.2 O.sub.5, As.sub.2 O.sub.5 As.sub.2 O.sub.3 ;N is chosen from the group formed by:SiO.sub.2 and GeO.sub.2 ;Q is chosen from the group formed by halogen anions and bi- or tri-valent mono- or poly-atomic anions exclusive of O.sup.2- ;O.ltoreq.x.ltoreq.0.35;O.ltoreq.y.ltoreq.0.8;O<a.ltoreq.2;O<b<1.5;b.ltoreq.2a; andz=1 or 2 or 3 according to whether Q is mono-, bi- or tri-valent.

Abstract: A method and apparatus for controlling a heated bath of molten material to obtain controlled solidification, wherein the molten bath is kept in constant rotational movement relative to the solid portion of the material being treated and the mechanical action due to the viscous friction which develops in the bath is detected and thereby controlled, said method being applicable to the floating zone method and the Czochralsky crystal drawing method and being capable of producing ingots of high dimensional regularity.

Abstract: Chromium dioxide CrO.sub.2 is prepared by oxidizing hydrated trivalent chromium oxide Cr.sub.2 O.sub.3, xH.sub.2 O, where x is at least 1, at a temperature of at least 350.degree. C and under pressures of at least 2 kilobars. The reaction is carried out in an oxidizing medium, which is a solid or an aqueous liquid solution, essentially constituted by a compound of the formula HXOy, zH.sub.2 O, wherein X represents an atom of chlorine or iodine, y is a positive integer less than or equal to 4, and z is a number which is a function of the dilution of said compound in the solution or a function of the crystallization water in the case of a solid oxidizing agent.The product is useful in any device requiring a compound which is ferromagnetic at a temperature less than 116.degree. C and notably in magnetic tapes.

Abstract: The invention relates to lamelliform oxides of high ionic conductivity which contain monovalent elements inserted between lamellae of oxides of the type (L.sub.x M.sub.1-x) O.sub.2 wherein L is a trivalent element, M is a tetravalent element and x is a number between 0 and 1. Such oxides are useful as solid electrolytes in electrochemical generators or cells.