Patent ID: 6398863
Filing Date: 2002-06-04
Classification: B82Y,C01G,C01P,G11B

Abstract:
Spindle-shaped hematite particles containing cobalt of 8 to 45 atm %, calculated as Co, based on whole Fe, aluminum of 5 to 20 atm %, calculated as Al, based on whole Fe, and a rare earth element of 1 to 15 atm %, calculated as rare earth element, based on whole Fe, and having an average particle size of 0.05 to 0.17 &mgr;m,each of said spindle-shaped hematite particles comprising a seed portion, an intermediate layer portion and an outer layer portion, the weight ratio of said seed portion to said intermediate layer portion being 30:70 to 80:20 and the relationship of the Co concentration of the seed portion with that of the hematite particle being 50 to 95:100 when the Co concentration of the hematite particle is 100, said aluminum existing only in said intermediate layer portion and said rare earth element existing in said outer layer portion.