| abstract |
Chromium dioxide CrO 2 is prepared by oxidizing hydrated trivalent chromium oxide Cr 2 O 3 , xH 2 O, where x is at least 1, at a temperature of at least 350° 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 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. n The product is useful in any device requiring a compound which is ferromagnetic at a temperature less than 116° C and notably in magnetic tapes. |