The ferrite particles for magnetic recording medium

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PROBLEM TO BE SOLVED : To provide hexagonal ferrite particles suitable for high-density magnetic recording media, particularly new ferrite particles for high-density perpendicular magnetic recording media suitable for a perpendicular magnetic recording system using magnetization in a direction perpendicular to a substrate surface. SOLUTION : The ferrite particles for magnetic recording media have an M type ferrite structure, comprises Ca, an element R which is at least one rare earth element and essentially includes La, Ba, Fe and Co as essential elements, and have a composition represented by general formula : Ca1-x-yRxBayFe2n-zCoz(atomic ratio), wherein (1-x-y), x, y, z and n represent contents of Ca, R, Ba and Co and a molar ratio and are numerical values satisfying 0.3≤1-x-y≤0.65, 0.2≤x≤0.65, 0.001≤y≤0.2, 0.03≤z≤0.65, 4≤n≤7 and 1-x-y>y. COPYRIGHT : (C)2009, JPO&INPIT