Process for the preparation of acicular alpha -FeOOH for magnetic recording materials

A process for preparing acicular alpha -FeOOH by partially neutralizing and then oxidizing a ferrous salt solution in the presence of phosphoric acid or a salt thereof to form seed crystals of alpha -FeOOH and optionally further oxidizing said solution while neutralizing said solution with an alkali...

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Bibliographic Details
Main Authors ISHIKAWA; TSUNEO, KAWAMURA; TOSHIHIKO, AMAMOTO; TARO, NAKATA; KAZUO
Format Patent
LanguageEnglish
Published 24.12.1985
Edition4
Subjects
BASIC ELECTRIC ELEMENTS
CHEMISTRY
COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSESC01D OR C01F
ELECTRICITY
INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OFSOLID INORGANIC COMPOUNDS
INDUCTANCES
INFORMATION STORAGE
INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORDCARRIER AND TRANSDUCER
INORGANIC CHEMISTRY
MAGNETS
METALLURGY
PHYSICS
SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
TRANSFORMERS
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Summary:A process for preparing acicular alpha -FeOOH by partially neutralizing and then oxidizing a ferrous salt solution in the presence of phosphoric acid or a salt thereof to form seed crystals of alpha -FeOOH and optionally further oxidizing said solution while neutralizing said solution with an alkali to grow said seed crystals, wherein pyrophosphoric acid or a salt thereof is used as said phosphoric acid and the seed crystals of alpha -FeOOH are formed at a temperature of 50 DEG to 100 DEG C. The alpha -FeOOH obtained according to the process of this invention is composed of fine particles and appreciably improved in acicularity and particle size distribution. Also, a magnetic recording medium made from the magnetic iron oxides derived therefrom in a usual way have a low noise characteristic and, are excellent in coercivity and other magnetic properties.
Bibliography:Application Number: US19840680241