PURPOSE: To obtain acicular γ-Fe2O3 particles maintaining its acicular form, preventing sintering among the particles and having a high transition temp. to α-Fe2O3 by coating the surfaces of γ-Fe2O3 particles with a metallic compd. contg. P, B, Ti or Al.
CONSTITUTION: A suspension prepd. by dispersing γ-Fe2O3 particles in water is mixed with a water soluble metallic compd. contg. one or more among P, B, Ti and Al and the mixture is stirred to coat the surfaces of the γ-Fe2O3 particles with the metallic compd. The transition temp. of the γ-Fe2O3 particles to α-Fe2O3 is raised and the objective particles are obtd. The pref. amt. of the metallic compd. coating the γ-Fe2O3 particles is 0.05-5wt.% (expressed in terms of the metallic element) of the amt. of the γ-Fe2O3. In the case of <0.05wt.%, the desired effects are hardly produced. In the case of >5wt.%, the metallic compd. adversely affects the magnetic characteristics such as saturation magnetization.
HORIO YUKO
OTANI TAKESHI
| JPS50151397A | 1975-12-05 | |||
| JPS5335698A | 1978-04-03 | |||
| JPS61132521A | 1986-06-20 | |||
| JPS6364305A | 1988-03-22 | |||
| JPS6461324A | 1989-03-08 | |||
| JPH01119519A | 1989-05-11 |