Neomax Co., Ltd.

Sumitomo Special Metals Co., Ltd.

Sumitomo Special Metal Co. Ltd.

Sachio Toyota

Seiichi Hosokawa

Etsushi Oda

Yoshinori Kobayashi

Isamu Furuchi

Shojiro Kawakami

Makoto Minakata

Shuji Anamoto

Mitsuhiro Takata

An oxide magnetic material according to the present invention is represented by the formula: (1&#x2212;x)CaO.(x/2)RO.(n&#x2212;y/2)FeO.yMO, where R is at least one element selected from the group consisting of La, Nd and Pr and always includes La, M is at least one element selected from the group consisting of Co, Zn, Ni and Mn and always includes Co, and the mole fractions x, y and n satisfy 0.4&#x2266;x&#x2266;0.6, 0.2&#x2266;y&#x2266;0.35, 4&#x2266;n&#x2266;6, and 1.4&#x2266;x/y&#x2266;2.5. The oxide magnetic material includes a ferrite having a hexagonal M-type magnetoplumbite structure as a main phase.

Oxide magnetic material and sintered magnet

A ferrite magnet obtained by adding a ferrite having a hexagonal W-type magnetoplumbite structure to a ferrite having a hexagonal M-type magnetoplumbite structure, in which a portion of Sr, Ba, Pb or Ca is replaced with at least one element that is selected from the group consisting of the rare-earth elements (including Y) and Bi and that always includes La, during the fine pulverization process thereof. By adding a small amount of the element such as Co, Ni, Mn or Zn to the ferrite already having the hexagonal M-type magnetoplumbite structure during the fine pulverization process thereof, the magnetic properties can be improved.

Permanent magnet and method for preparation thereof

A ferrite magnet obtained by adding at least one element selected from the group consisting of Co, Ni, Mn and Zn to a ferrite having a hexagonal M-type magnetoplumbite structure, in which a portion of Sr, Ba, Pb or Ca is replaced with at least one element that is selected from the group consisting of the rare-earth elements (including Y) and Bi and that always includes La, during the fine pulverization process thereof, and then subjecting the mixture to re-calcining and/or sintering process(es). By adding a small amount of the element such as Co, Ni, Mn or Zn to the ferrite already having the hexagonal M-type magnetoplumbite structure during the fine pulverization process thereof, the magnetic properties can be improved.

A ferrite magnet obtained by adding a ferrite having a spinel-type structure to a ferrite having a hexagonal M-type magnetoplumbite structure, in which a portion of Sr, Ba, Pb or Ca is replaced with at least one element that is selected from the group consisting of the rare-earth elements (including Y) and Bi and that always includes La, during the fine pulverization process thereof. By adding a small amount of the element such as Co, Ni, Mn or Zn to the ferrite already having the hexagonal M-type magnetoplumbite structure during the fine pulverization process thereof, the magnetic properties can be improved.

A ferrite magnet obtained by adding either an oxide of Mn or oxides of Mn and Co to a ferrite having a hexagonal M-type magnetoplumbite structure, in which a portion of Sr, Ba, Pb or Ca is replaced with at least one element that is selected from the group consisting of the rare earth elements (including Y) and Bi and that always includes La, during the fine pulverization process thereof, and then subjecting the mixture to re-calcining and/or sintering process(es). By adding a small amount of the element Mn or elements Mn and Co to the ferrite already having the hexagonal M-type magnetoplumbite structure during the fine pulverization process thereof, the magnetic properties can be improved.

A ferrite magnet powder and a ferrite magnet exhibiting improved magnetic properties are provided at a reduced manufacturing cost. An application product and manufacturing methods thereof are also provided. An oxide magnetic material includes, as a main phase, a ferrite having a hexagonal M-type magnetoplumbite structure. The material includes: A, which is at least one element selected from the group consisting of Sr, Ba, Pb and Ca; R, which is at least one element selected from the group consisting of Y (yttrium), the rare earth elements and Bi; Fe; and B (boron). The constituents A, R, Fe and B of the material satisfy the inequalities of 7.04 at %&#x2266;A&#x2266;8.68 at %, 0.07 at %&#x2266;R&#x2266;0.44 at %, 90.4 at %&#x2266;Fe&#x2266;92.5 at % and 0.015 at %&#x2266;B&#x2266;0.87 at % to the sum of the elements A, R, Fe and B.

Oxide magnetic material

The production is performed by calcining ferrite magnetic powder in which La is substituted for part of Sr and Ti, Zn, and Co are substituted for part of Fe at temperatures of 1100&deg; C. to 1450&deg; C. The magnetization is improved by substituting Zn for part of Fe, and by substituting Ti for part of Fe for the purpose of charge compensation. In addition, the coercive force is improved by substituting Co for part of Fe, and by substituting La for part of Sr for the purpose of charge compensation. Ti is used for the charge compensation, so that it is possible to reduce the cost.

Magnet powder and method for preparations thereof

An La&mdash;Co ferrite magnet powder, in which Sr and Fe are replaced with La and Co, respectively, is made by carrying out a calcination process at a temperature higher than 1300&deg; C. and equal to or lower than 1450&deg; C. Fe has a magnetic moment oriented upwardly with respect to a crystal c-axis at a number of sites thereof, and also has an opposite magnetic moment oriented downwardly with respect to the crystal c-axis at another number of sites thereof. And Fe is replaced with Co at the greater number of sites thereof. As a result, high coercivity is attained. In this manner, coercivity can be increased while suppressing decrease in saturation magnetization &sgr; .

Ferrite magnet powder and magnet using said magnet powder, and method for preparing them

Ferrite magnet, and powder for ferrite magnet and production process

A method of manufacturing a transparent, high density green material which comprises: sintering a PLZT ceramic compact in a vacuum of 1.times.10.sup.-2 to 1.times.10.sup.-5 Torr at 1150.degree. C. to 1250.degree. C. for 0.5 to 2 hours, fabricating the sintering product into a sheet of less than 1.5 mm thickness, embedding the sheet into a heat resistant vessel tightly packed with a powder of 50 .mu.m to 3000 .mu.m grain size comprising at least one of fused alumina, zirconia and magnesia and then applying HIP under 500 to 700 kg/cm.sup.2, at 1050.degree. C. to 1200.degree. C., for 0.5 to 2 hours by using an inert gas as a pressure medium. Ceramics for optical devices having high transparency and density can be mass produced economically in a short time.

Method of manufacturing transparent high density ceramic material

There is disclosed an optical switch comprising an optical fiber, a block of PLZT, and two polarizers disposed on opposite sides of the block. The fiber has one or more grooves in which the block and the polarizers are received. The block of PLZT induces an electric field perpendicular to the axis of the core of the fiber. The groove or grooves extend across the core of the fiber such that the block covers the whole cross section of the core. Each polarizer consists of alternate laminations of a metal and a dielectric. The laminations are stacked in a direction perpendicular to the axis of the core. Each dielectric lamination is thicker than each metal lamination. If incident light is polarized, one of the polarizers is omitted.

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Saga, Japan

Sachio Toyota