Abstract: The present invention relates to carbon nanotubes that are excellent in dispersibility and a process for producing the carbon nanotubes. The carbon nanotubes according to the present invention each comprise a wall that comprises a parallel portion and a narrowed portion having a tube outer diameter that is not more than 90% of a tube outer diameter of the parallel portion. Thus, the carbon nanotubes are readily dispersible owing to a high abundance ratio of easily-breaking portions.

Abstract: The present invention relates to carbon nanotubes that are excellent in dispersibility and a process for producing the carbon nanotubes. The carbon nanotubes according to the present invention each comprise a wall that comprises a parallel portion and a narrowed portion having a tube outer diameter that is not more than 90% of a tube outer diameter of the parallel portion. Thus, the carbon nanotubes are readily dispersible owing to a high abundance ratio of easily-breaking portions.

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 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 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 plate-like composite ferrite fine particles for magnetic recording comprising plate-like composite ferrite containing Ba fine particles which contain Ti of 2 to 5.0 atomic % based on Fe.sup.3+ and Ni in the range of 1.2.ltoreq.Ni/Ti.ltoreq.4 by molar ratio, which have zinc in the vicinity of the particles surfaces in the form of a solid solution, which have an average particle diameter of 0.01 .mu.m to 0.08 .mu.m, and the coercive force of which scarcely varies with the rise in temperature in the temperature range of -20.degree. C. to 120.degree. C., and a process for producing such plate-like composite ferrite fine particles.

Abstract: Disclosed herein are plate-like composite ferrite particles for magnetic recording comprising plate-like composite ferrite containing Ba particles having a composition represented by 19<(Fe+M)/Ba.ltoreq.22, wherein M represents at least one metal (II) selected from the group consisting of Co, Ni, Zn, Mn and Mg and at least one metal (IV) selected from the group consisting of Ti, Sn, Zr and Ge, in which Ba exists in the composition at a linear concentration gradient between the surface and the nucleation portion of said particles, and a process for producing such plate-like composite ferrite particles.

Abstract: Disclosed herein are plate-like barium ferrite particles with a solid solution of zinc on the surface thereof, which have an average particle diameter of not less than 0.03 .mu.m and less than 0.1 .mu.m, a BET specific surface are of 55 to 80 m.sup.2 /g, a coercive force of 300 to 1,500 Oe and a magnetization of not less than 57 emu/g, preferably not less than 60 emu/g, in magnetic field of 10 KOe, and which are represented by the following formula (I):BaO.n[(Fe.sub.1-x-y Co.sub.x Ti.sub.y).sub.2 O.sub.3-x+y ] (I)wherein x and y are independently from 0.02 to 0.12 and n is from 4 to 11, the atomic ratio of Co to Fe(III) being from 0.02:1 to 0.13:1 and the molar ratio of Ti to Co being from more than 0 to not more than 0.8, and a process for producing the plate-like barium ferrite particles.

Abstract: Disclosed herein are plate-like barium ferrite particles with a solid solution of zinc on the surface thereof, which have an average particle diameter of 0.05 to 0.3 .mu.m, a coercive force of 300 to 1,500 Oe and a magnetization of not less than 55 emu/g in magnetic field of 10 KOe, and which are represented by the following formula (I):BaO.multidot.n[(Fe.sub.1-2x Co.sub.x Ti.sub.x).sub.2 O.sub.3 ](I)wherein x is 0 to 0.1 and n is from 4 to 11, the molar ratio of Ti to Co being 1, and a process for producing the plate-like barium ferrite particles.

Abstract: Disclosed herein are Ba-containing plate-like magnetoplumbite type ferrite particles for magnetic recording containing ions of one metal (II) selected from Ni and Zn and ions of one metal (IV) selected from Ti, Sn and Zr, and having zinc incorporated as a solid solution close to the particle surface and the change of coercive force of said particles at a temperature of -20.degree. to 120.degree. C. in the range of -0.5 to +0.5 Oe/.degree.C., and a process for producing the same.

Abstract: Disclosed herein are plate-like barium particles which are suitable for use in precursor of sintered magnets and magnetic recording media, which have an average particle diameter of not less than 0.03 .mu.m and less than 0.1 .mu.m, and which are represented by the following formula (I):BaO.n[Fe.sub.1-x-y Co.sub.x Ti.sub.y).sub.2 O.sub.3-x+y ] (i)wherein x and y are independently from 0.02 to 0.12 and n is from 4 to 7, the atomic ratio of Co to Fe(III) being from 0.02:1 to 0.13:1 and the molar ratio of Ti to Co being from more than 0 to not more than 0.8, and a process for producing the plate-like barium ferrite particles.

Abstract: Disclosed herein are hexagonal plate-like barium ferrite particles for magnetic recording, represented by the formula: BaFe.sub.12-x-y M.sub.x Ti.sub.y O.sub.19 wherein x and y are independently 0.6 to 1.2 and M is Co(II) or Co(II) and a divalent metal other than Co, having the width of the particle of 0.1 to 0.4 micrometer and a BET specific surface area (S) of 20 to 50 m.sup.2 /g, and showing a magnetization (M) of larger than 40 emu/g in a magnetic field of 10 KOe and a coercive force (Hc) of 500 to 1000 Oe, and a process for producing the same.

Abstract: Disclosed herein are plate-like barium ferrite particles having BET specific surface area of 20 to 70 m.sup.2 /g and average particle diameter of 0.05 to 0.3 .mu.m, and showing a magnetization of higher than 30 emu/g in a field of 10 kOe and coercive force of 300 to 1,000 Oe, represented by the formula BaCo.sub.x Ti.sub.x Fe.sub.12-2x O.sub.19 wherein x is 0.1 to 0.5, and a process for producing the same.

Abstract: Disclosed herein are plate-like barium ferrite particles for magnetic recording, comprising plate-like particles represented by the formula:BaFe.sub.12-2x M.sub.x Ti.sub.x O.sub.19wherein x is 0 to 1.2 and M represents Co (II) or Co (II) and a divalent metal ion other than Co (II), the surface of the plate-like particles being modified with magnetite represented by the formula:FeO.sub.y.Fe.sub.2 O.sub.3wherein y is over 0 and not more than 1, and a process for producing the same.

Abstract: Disclosed herein is a process for producing the plate-like barium ferrite particles represented by the formula (I):BaFe.sub.12-x-y M.sub.x Ti.sub.y O.sub.19 (I)wherein x and y are respectively 0.3 to 1.2 and M is a divalent metal selected from the group consisting of Co, Ni, Zn and Mn, which comprises autoclaving an aqueous highly alkaline suspension containing spinel particles represented by the formula: Fe.sub.12-x-y M.sub.x Ti.sub.y O.sub.16, wherein x, y and M are respectively the same as defined above, having an average particle size of less than 0.1 .mu.m and Ba ions at a temperature of 250.degree. to 330.degree. C., the atomic ratio of Ba to total amount of the metals being in a range from 1:8 to 1:10.

Abstract: Disclosed herein are the plate-like barium ferrite particles for use in magnetic recording, showing a specific surface area of 11 to 50 m.sup.2 /g, a value of magnetization of higher than 25 emu/g in a magnetic field of 10 KOe and a coercive force of 600 to 1100 Oe, and a process for producing the same.

Abstract: Barium ferrite particles of a coercive force of not more than 1,000 Oe suitable for use as a magnetic material for magnetic recording and a process for producing said particles are disclosed herein.

Abstract: Disclosed herein is a process for producing plate-like barium ferrite particles for magnetic recording, represented by the formula:BaFe.sub.12-x-y M.sub.x Ti.sub.y O.sub.19wherein x and y are independently not more than 1.2 and M is Co(II) or Co(II) and a divalent metal other than Co, which comprises adding a compound of Si(IV) to an aqueous highly alkaline suspension of ferric hydroxide containing Ti(IV), Ba(II) and Co(II) or Co(II) and a divalent metal other than Co as M(II), and autoclaving the resultant aqueous highly alkaline suspension of ferric hydroxide at the temperature of 200.degree. to 330.degree. C., thereby obtaining the plate-like barium ferrite particles having the thickness thereof controlled according to the atomic ratio of Si(IV) to Fe(III).