Abstract: Disclosed herein are spindle-shaped magnetic iron based alloy particles containing at least one selected from the group consisting of Ni, Al, Si, P, Co, Mg, B and Zn, which have a particle length of 0.05 to 0.40 .mu.m, a crystallite size of 110 to 180 .ANG., a specific surface area of 30 to 60 m.sup.2 /g, a coercive force of 1,300 to 1,700 Oe and a saturation magnetization (.sigma.s) of not less than 100 emu/g and a process for producing the same.

Abstract: Disclosed herein are magnetic iron oxide particles which have a spindle shape and a substantially uniform particle size and shape, and are substantially free of dendrites and have a large axial ratio (major axial diameter/minor axial diameter) and an excellent print-through characteristic, and a method of producing the same.

Abstract: Disclosed herein are spindle-shaped magnetic iron based alloy particles containing at least one selected from the group consisting of Ni, Al, Si, P, Co, Mg, B and Zn, which have a particle length of 0.05 to 0.40 .mu.m, a crystallite size of 110 to 180 .ANG., a specific surface area of 30 to 60 m.sup.2 /g, a coercive force of 1,300 to 1,700 Oe and a saturation magnetization (.sigma.s) of not less than 100 emu/g and a process for producing the same.

Abstract: Disclosed herein are magnetic iron oxide particles which have a spindle shape and a substantially uniform particle size and shape, and are substantially free of dendrites and have a large axial ratio (major axial diameter/minor axial diameter) and an excellent print-through characteristic, and a method of producing the same.

Abstract: Disclosed herein are acicular magnetic iron based alloy particles for magnetic recording, containing 1.5 to 10 mol % of B based on Fe (calculated as B) and 1.5 to 10 mol % of Co based on Fe (calculated as Co) in the vicinity of the surfaces of said particles and having a saturation magnetization of not less than 125 emu/g and an S.F.D. value of not more than 0.50, and a process for producing the same.

Abstract: Disclosed herein are acicular magnetic iron based alloy particles for magnetic recording, containing 1.5 to 10 mol % of B based on Fe (calculated as B) and 1.5 to 10 mol % of Co based on Fe (calculated as Co) in the vicinity of the surfaces of said particles and having a saturation magnetization of not less than 125 emu/g and an S.F.D. value of not more than 0.50, and a process for producing the same.

Abstract: Disclosed herein are acicular magnetic metal particles containing iron as the main ingredient the surfaces of which are coated with a polymer formed from at least one of silicone compounds represented by the following formula (I):(R.sup.1 HSiO).sub.a (R.sup.2 R.sup.3 SiO).sub.b (R.sup.4 R.sup.5 R.sup.6 SiO.sub.1/2)c (I)wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 respectively represent a hydrogen atom or hydrocarbon group having 1 to 10 carbon atoms which hydrocarbon group may be substituted by at least one halogen atom, a and b are respectively 0 or integers of not less than 1, and c is 0 or 2, provided that when c is 0, the sum of a and b is an integer of not less than 3 and which have a coercive force of not less than 1400 Oe, a saturation magnetization of not less than 100 emu/g, a major axial diameter of not more than 0.25 .mu.m and an S.F.D. of not more than 0.38, and a process for producing the acicular magnetic metal particles containing iron as the main ingredient.

Abstract: Plate-like magnetite particles, plate-like maghemite particles and the processes for producing these particles are herein disclosed. The plate-like magnetite particles and the plate-like maghemite particles provided according to the present invention are fine plate-like particles which are poreless and non-sintered as the plate-like magnetite particles are produced directly from an aqueous solution and these plate-like magnetite particles are oxidized by heating to produce the plate-like maghemite particles. Therefore, these particles can be filled to a high density in a vehicle or resin, have good dispersibility and orientability and are also high in a degree of particle contact, so that they are suited for use as electromagnetic wave absorbing and shielding material, magnetic material for magnetic recording, black or brown pigment for paints and colorant for rubber and plastic products.