Process for the preparation of magnetized hexagonal ferrites, use of these ferrites as base materials for magnets or for magnetic recording

摘要

Magnetic hexagonal ferrites, in which ferrites the iron atom may be optionally substituted (substituted or unsubstituted barium hexaferrites, etc.), are prepared in high yields, and under non-corrosive conditions by a hydrothermal synthesis reaction between at least one alkali metal ferrite and a compound which releases an alkaline-earth metal ion in water (baryta, etc.) and optionally one or more alkali metal salt(s) of metal oxides. Magnetic hexagonal ferrites can be used as materials for permanent magnets and for ultrahigh frequency components or for magnetic recording materials. For example, ferromagnetic particles having a specific magnetization of at least 65 emu/g and a coercive field strength of at least 2500 oersteds can be prepared.