Toda Kogyo Corporation

Katsunori Fujimoto

Yasutaka Ota

Norimichi Nagai

Masao Kiyama

Toshio Takada

Akihiko Hirayama

Kenji Okinaka

Tosiharu Harada

Kohji Mori

Norio Sugita

Akio Mishima

Hirofumi Kawasaki

Mamoru Tanihara

Yoshiro Okuda

Tsutomu Katamoto

Minoru Yamasaki

Katsumi Yamashita

Toshitada Shigemura

Cobalt-coated acicular magnetic iron oxide particles of the present invention have an average major axial diameter of 0.15 to 0.50 .mu.m, and comprise:

Cobalt-coated acicular magnetic iron oxide particles

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.

Spindle-shaped magnetic iron based alloy particles and process for

Spindle-shaped magnetic iron based alloy particles

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):

Plate-like barium ferrite particles suitable for use in magnetic

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):

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.

Plate-like magnetoplumbite ferrite particles for magnetic recording and

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):

Process for producing plate-like barium ferrite particles

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Hiroshima, Japan

Katsunori Fujimoto