Magnetic fine particulate isometric doped iron oxide

摘要

Magnetic fine particulate isometric doped iron oxide of compsn. FeOx (x = 1.33-1.5) is novel in that the iron oxide has a phosphorous content of /- 0.1 wt.% and is opt. additionally doped with transition metal or alkali metal cations. It possesses the following characteristics data intrinsic coercive force Hc of less than 12 kA/m, residual coercive force Hr of less than 15kA/m, the ratio Hr/Hc being <= 2, and specific residual magnetisation or above 10 Am<2>/g. Also claimed is a magnetic recording medium comprising a non-magnetic film base and /- one coating thereon. In the coating, magnetic pigments comprising the above iron oxide are finely distributed in one or several polymeric binders. The magnetic recording medium is characterised by having the following magnetic characteristics; Hc of less than 12 kA/m, Hr of less than 15 kA/m, and residual magnetic induction Br of above 50 mT. Also claimed is a process for mfg. the above magnetic fine particulate isomeric doped iron oxide.