Acicular hematite particles and magnetic recording medium

摘要

Acicular hematite particles suitable for use as a non-magnetic substrate in the manufacture of a magnetic recording medium, which contain from 0.05 to 30% by weight of zirconium within the particles, calculated as Zr, based on the total weight of the particles, not more than 300 ppm of soluble sodium salt, calculated as Na and not more than 150 ppm of soluble sulfate, calculated as SO4; and which have an average major axis diameter of not more than 0.3 mu m and a pH value of not less than 8.