摘要:
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.2 as well as eventually (3) of dilution water and/or of at least an additional doping agent acting as buffer in the reaction medium and/or a conventional modifying agent.The invention is useful for the manufacture of a ferromagnetic material possessing improved magnetic characteristics.
摘要:
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.
摘要翻译:二氧化铬CrO 2通过在至少350℃的温度和至少2千瓦的压力下氧化水合的三价铬氧化物Cr 2 O 3,xH 2 O,其中x至少为1来制备。 反应在氧化性介质中进行,该氧化介质是固体或水性液体溶液,其基本上由式HXOy,zH2O的化合物构成,其中X表示氯原子或碘原子,y是小于或等于 等于4,z是在溶液中所述化合物的稀释度或在固体氧化剂情况下结晶水的作用的函数的数。
摘要:
The rare earth borides, e.g., the tetraborides and hexaborides of lanthanum, cerium and praseodymium, are directly prepared by heating/reacting a mixture of at least one rare earth chloride and elemental boron at an elevated temperature, e.g., a temperature ranging from 1,200.degree. to 1,500.degree. C.
摘要:
The rare earth borides are prepared at relatively low temperatures by reacting a rare earth halide with elemental boron in the presence of a reducing amount of aluminum metal.
摘要:
Novel compositions containing finely divided barium titanate particulates homogeneously dispersed in a solid organic matrix material, the barium titanate particles having a mean diameter of at least 1 micron, are well adopted for the production of electromagnetic wave absorbers, e.g., seals for microwave ovens.
摘要:
Particulates, e.g., powders, of the rare earth borides are well suited for the effective abrasion/polishing of a variety of characteristically hard substrate face surfaces, e.g., hard ceramic surfaces.