Tin-containing granular magnetic oxide particles and process for producing the same

摘要

Tin-containing granular magnetic oxide particles comprising spinel-type crystal represented by the formula:wherein x is 0.14 to 0.48, andhaving a Fe2+ content of 17 to 22% by weight, a lattice constant of 8.41 to 8.49 Å, a magnetization value of 20 to 50 Am2/kg when measured under an applied magnetic field of 79.6 kA/m, and a depth of a groove of not more than 40 mum at which three or more continuous lines each having a length of not less than 10 mm are developed in a pigment dispersion test using a grind-meter when measured by Hoover's muller method according to JIS K5101 (1991) 9.1. The tin-containing granular magnetic oxide particles of the present invention exhibit a sufficient blackness, a small magnetization value and an excellent dispersibility.