| 摘要 |
PURPOSE:To produce hexagonal ferrite powder used for a vertical magnetic recording medium capable of being made to uniform high-recording density by adding specified metal in case of hydrothermal treatment of a compd. contg. both a compd. producing hydrated iron oxide and iron hydroxide and Ba, Sr and Pb or the like. CONSTITUTION:The hexagonal ferrite shown in a general formula (I) is calcined in the presence of a BaCl2-NaCl flux to produce hexagonal ferrite powder excellent in magnetic characteristics. Said hexagonal ferrite is obtained by using alpha-FeOOH (goethite) and delta-FeOOH as hydrated iron oxide and using Fe(OH)3 and Fe(OH)2 as iron hydroxide or using iron chloride, iron nitrate and iron sulfate, etc., as a compd. producing iron hydroxide and hydrated iron oxide by reaction and using chloride, nitrate and hydroxide of Ba, Sr and Pb as an auxiliary raw material and furthermore using a compd. of Co-T-M (M is one or more kinds selected from among Sb, Sn, W and In). |
