Method for the preparation of fine hexagonal ferrite powders, in particular, for magnetic recording

• Main Authors: RINALDI, STEFANO, LICCI, FRANCESCA, BESAGNI, TULLO
• Format: Patent
• Language: English; French; German
• Published: 16.04.1986
• Edition: 4
• Subjects: ADHESIVES; BASIC ELECTRIC ELEMENTS; CHEMICAL PAINT OR INK REMOVERS; CHEMISTRY; COATING COMPOSITIONS, e.g. PAINTS, VARNISHES ORLACQUERS; COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSESC01D OR C01F; CORRECTING FLUIDS; DYES; ELECTRICITY; FILLING PASTES; INDUCTANCES; INFORMATION STORAGE; INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORDCARRIER AND TRANSDUCER; INKS; INORGANIC CHEMISTRY; MAGNETS; METALLURGY; MISCELLANEOUS APPLICATIONS OF MATERIALS; MISCELLANEOUS COMPOSITIONS; NATURAL RESINS; PAINTS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; PHYSICS; POLISHES; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES; TRANSFORMERS; USE OF MATERIALS THEREFOR; WOODSTAINS

The method disclosed by which to prepare fine hexagonal ferrites for use in magnetic recording, is one which consists basically in dissolving a) carbonates or other soluble compounds of an alkaline earth metal such as strontium or barium, b) a carbonate or other soluble compound of cobalt, and c) titanium trichloride, all in a solution of ferric citrate and water, whereupon a polycondensation is brought about by addition of ethylene clycol, and heat is applied to eliminate water and organic matter from the compound. Addition of the alkaline earth metal, the cobalt and the titanium is proportioned precisely on the basis of the stoichiometric properties of the end-product, the formula for which iswhere x is the extent to which cobalt and titanium atoms replace iron atoms and Re is the alkaline earth metal. Final application of heat produces crystallization of the superfine hexaferrite particles.