| 摘要 |
PROBLEM TO BE SOLVED: To improve needle like property as a fine particle shape by specifying Co/Fe ratio in Co containing needle-like goethite fine particle, adding alkali carbonate to soil suspension thereof to specify the mole ratio of carbonate ion to ferric ion and aging it. SOLUTION: A ferric salt solution containing Co salt is adjusted by dissolving Co salt and ferric salt to water. In the process, the ratio of Co salt to ferric salt is selected to make Co/Fe ratio in finally obtained Co containing needle like goethite fine particles which does not exceed about 15 at%. Then, strong akalline solution is mixed with the Co salt containing ferric salt solution and is agitated, and soil suspension is formed. Alkali carbonate is added to the soil suspension to make the mole ratio of carbonate ion to ferric ion to be about 6.0 or more and about 10.0 or less and is aged. Thereby, twin-free Co containing needle-like goethite fine particles which have fine grain diameter and are superior in needle-like property is manufactured. |
