| 摘要 |
PROBLEM TO BE SOLVED: To obtain a hexagonal ferrite particulate powder having an average plate surface diameter of 10-20.5 nm, by a hydrothermal synthesis method excellent in industrial productivity.SOLUTION: A method for producing a hexagonal ferrite particulate powder is obtained by the following steps: adding a suspension of a mixture of a metal salt containing at least one of metal ion selected from among barium, strontium and calcium, an iron compound, and one or more kinds of metal salts selected from divalent to pentavalent metal elements to an aqueous alkali solution; bringing these into a reaction in a temperature range of 100-300°C using an autoclave; separating the resulting precursor of a hexagonal ferrite particulate by filtration and drying it; firing it at a temperature of 600-780°C in the presence of a flux; and removing the flux; wherein the suspension is slowly added to the aqueous alkali solution over ≥20 minutes, whereby the objective hexagonal ferrite particulate powder can be obtained. |
