Iron-based oxide magnetic particle powder and method for producing iron-based oxide magnetic particle powder

A method for producing an iron-based oxide magnetic particle powder in which a part of Fe sites of ε-Fe2O3 is substituted with another metal element, having a mean particle diameter as measured by a transmission electron microscopy of 10 nm to 30 nm, the method comprising:

• a first neutralization step in which an aqueous solution containing trivalent iron ions and ions of the metal for partially substituting the Fe sites is neutralized to a pH of 1.5 to 2.5;
• a step in which a hydroxycarboxylic acid is added to the aqueous solution after the neutralization;
• a second neutralization step in which the aqueous solution having the hydroxycarboxylic acid added is neutralized to a pH of 8.0 to 9.0;
• a step in which an iron oxyhydroxide containing the substituting metal element produced in the second neutralization step is subjected to water washing;
• a step in which the iron oxyhydroxide containing the substituting metal element after the water washing is coated with a silicon oxide;
• and
• a step in which the iron oxyhydroxide containing the substituting metal element coated with the silicon oxide is heated to produce an iron oxide containing the substituting metal element coated with the silicon oxide.

A method for producing an iron-based oxide magnetic particle powder in which a part of Fe sites of ε-Fe2O3 is substituted with another metal element, having a mean particle diameter as measured by a transmission electron microscopy of 10 nm to 30 nm, the method comprising:

• a first neutralization step in which an aqueous solution containing trivalent iron ions and ions of the metal for partially substituting the Fe sites is neutralized to a pH of 1.5 to 2.5;
• a step in which a hydroxycarboxylic acid is added to the aqueous solution after the neutralization;
• a second neutralization step in which the aqueous solution having the hydroxycarboxylic acid added is neutralized to a pH of 8.0 to 9.0;
• a step in which an iron oxyhydroxide containing the substituting metal element produced in the second neutralization step is subjected to water washing;
• a step in which the iron oxyhydroxide containing the substituting metal element after the water washing is coated with a silicon oxide;
• a step in which the iron oxyhydroxide containing the substituting metal element coated with the silicon oxide is heated to produce an iron oxide containing the substituting metal element coated with the silicon oxide;
• and
• a step in which the silicon oxide coating the iron oxide containing the substituting metal element is removed.

A method for producing an iron-based oxide magnetic particle powder in which a part of Fe sites of ε-Fe2O3 is substituted with another metal element, having a mean particle diameter as measured by a transmission electron microscopy of 10 nm to 30 nm, the method comprising:

• a first neutralization step in which an aqueous solution containing trivalent iron ions and ions of the metal for partially substituting the Fe sites is neutralized to a pH of 1.5 to 2.5;
• a step in which a hydroxycarboxylic acid is added to the aqueous solution after the neutralization;
• a second neutralization step in which the aqueous solution having the hydroxycarboxylic acid added is neutralized to a pH of 8.0 to 9.0;
• a step in which an iron oxyhydroxide containing the substituting metal element produced in the second neutralization step is subjected to water washing;
• a step in which the iron oxyhydroxide containing the substituting metal element after the water washing is coated with a silicon oxide;
• a step in which the iron oxyhydroxide containing the substituting metal element coated with the silicon oxide is heated to produce an iron oxide containing the substituting metal element coated with the silicon oxide;
• and
• a step in which the silicon oxide coating the iron oxide containing the substituting metal element is removed and then the iron oxide containing the substituting metal element is classified.

A method for producing an iron-based oxide magnetic particle powder in which a part of Fe sites of ε-Fe2O3 is substituted with another metal element, having a mean particle diameter as measured by a transmission electron microscopy of 10 nm to 30 nm, the method comprising:

• a first neutralization step in which an aqueous solution containing trivalent iron ions and ions of the metal for partially substituting the Fe sites is neutralized to a pH of 1.5 to 2.5;
• a step in which a hydroxycarboxylic acid is added to the aqueous solution after the neutralization;
• a second neutralization step in which the aqueous solution having the hydroxycarboxylic acid added is neutralized to a pH of 8.0 to 9.0;
• a step in which an iron oxyhydroxide containing the substituting metal element produced in the second neutralization step is subjected to water washing;
• a step in which a hydrothermal treatment at 120° C. to 180° C. is applied to the iron oxyhydroxide containing the substituting metal element after the water washing;
• a step in which the iron oxyhydroxide containing the substituting metal element after the hydrothermal treatment is coated with a silicon oxide;
• a step in which the iron oxyhydroxide containing the substituting metal element coated with the silicon oxide is heated to produce an iron oxide containing the substituting metal element coated with the silicon oxide;
• and
• a step in which the silicon oxide coating the iron oxide containing the substituting metal element is removed.