PURPOSE: The title powdery fine ferrite particles having appropriate coercive force and high thermal stability consisting of plate magnetoplumbite type ferrite particles having a specified compsn. contg. Ba wherein the change of coercive force of said Ba is regulated within a specified range.
CONSTITUTION: The powdery plate magnetoplumbite type fine ferrite particles to be used for magnetic recording of this invention have a compsn. expressed by the formula and consist of plate magnetoplumbite type fine ferrite particles contg. Ba having a coercive force changeable within a range from -2.0W+2.0Oe/°C at 20W120°C. For the prepn. of said fine particles, a Ba material such as BaCO3, an Fe material such as hematite, a Zn (as substituting element) material such as ZnO, a Ti material such as TiO2, and a Co material, are mixed in a specified proportion. Then, the mixture is calcined at 750W950°C in the presence of a flux, crushed coarsely thereafter, and washed by the conventional process with water or an acid, etc.
FUJITA TATSUJI
SANADA KAZUTOSHI
HORIISHI NANAO
| JPS6081804A | 1985-05-09 | |||
| JPS6012973A | 1985-01-23 | |||
| JPS61275130A | 1986-12-05 | |||
| JPS63164203A | 1988-07-07 |