Toda Kogyo Corporation

Norio Sugita

Kazuyuki Hayashi

Hiroko Morii

Norimichi Nagai

Minoru Ohsugi

Masaaki Maekawa

Keisuke Iwasaki

Yasuyuki Tanaka

Toshio Takada

Masao Kiyama

Mineko Sakoda

Yoji Okano

Yasutaka Ota

Katsunori Fujimoto

Akihiko Hirayama

Nanao Horiishi

Tomohiro Dote

Takayuki Yoshida

A Ni&#x2014;Zn&#x2014;Cu ferrite material having excellent DC bias characteristics is provided by adding zinc silicate thereto. The above problem can be solved by Ni&#x2014;Zn&#x2014;Cu ferrite particles which comprise a spinel-type ferrite and zinc silicate, which have a composition comprising 36.0 to 48.5 mol % of FeO, 7.0 to 38 mol % of NiO, 4.5 to 40 mol % of ZnO, 5.0 to 17 mol % of CuO and 1.0 to 8.0 mol % of SiO, all amounts being calculated in terms of the respective oxides, and which have a ratio of an X-ray diffraction intensity from a 113 plane of the zinc silicate to an X-ray diffraction intensity from a 311 plane of the spinel-type ferrite is 0.01 to 0.12; a green sheet obtained by forming a material comprising the Ni&#x2014;Zn&#x2014;Cu ferrite particles into a film; and a Ni&#x2014;Zn&#x2014;Cu ferrite sintered ceramics.

Ni&#x2014;Zn&#x2014;Cu ferrite particles, green sheet comprising the Ni&#x2014;Zn&#x2014;Cu ferrite particles and Ni&#x2014;Zn&#x2014;Cu ferrite sintered ceramics

Soft-magnetic hexagonal ferrite composite particles composed of 100 parts by weight of soft-magnetic hexagonal ferrite particles containing a Z-type ferrite, Y-type ferrite or W-type ferrite as a main phase, 0.3 to 10 parts by weight of barium carbonate particles, strontium carbonate particles or their mixture and 0.1 to 5 parts by weight of silicon dioxide particles.

Soft-magnetic hexagonal ferrite composite particles, and green sheet using the same and soft-magnetic hexagonal ferrite sintered ceramics

The disclosure describes a non-magnetic undercoating layer for a magnetic recording medium, coated on the surface of a non-magnetic substrate comprising:

Non-magnetic coated particles having a defined parameter .alpha. of not

Non-magnetic undercoating layer for magnetic recording medium, magnetic

Non-magnetic undercoat layer for magnetic recording medium, magnetic

Disclosed herein magnetic particles for magnetic recording which comprise acicular or plate-like magnetic particles and not less than 0.01 wt % (calculated as Al, SiO.sub.2 or Al and SiO.sub.2 and based on the acicular or plate-like magnetic particles) of an oxide or hydroxide containing Al, Si or both Al and Si and adhered to the surfaces of the acicular or plate-like magnetic particles, and which have not less than 0.50 of a molecular-weight-dependent parameter .alpha. represented by the following formula (I):

Magnetic particles for magnetic recording medium and process for

Disclosed herein are plate-like composite Ba-containing ferrite fine particles for magnetic recording, containing Ni, Co and Ti in the molar ratios defined by 0.02.ltoreq.Ni/Fe.ltoreq.0.10, 0.01.ltoreq.Co/Fe.ltoreq.0.10 and 0.01.ltoreq.Ti/Fe.ltoreq.0.10, but 0.03.ltoreq.(Ni+Co)/Fe.ltoreq.0.14 and Ti/(Ni+Co)&lt;1, and having zinc in the vicinity of the particle surface in the form of solid solution, and a temperature dependence of coercive force of said particles in the range of -0.5 to +2.0 Oe/.degree.C. in the temperature range of -20.degree. to 120.degree. C., and a process for producing the same.

Plate-like composite ferrite fine particles for magnetic recording and a

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.

Plate-like composite ferrite fine particles suitable for use in magnetic

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&lt;(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.

Plate-like composite ferrite particles for magnetic recording and

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 plate-like barium ferrite particles for magnetic recording, comprising plate-like particles represented by the formula:

Growing community of inventors

Hiroshima, Japan

Norio Sugita