Shin-etsu Chemical Co., Ltd.

Ge Yokogawa Medical Systems, Limited

Mitsubishi Denki Kabushiki Kaisha

Kawasaki Jukogyo Kabushiki Kaisha

Shin-etsu Chemical Ci., Ltd.

Ken Ohashi

Yoshio Tawara

Tadao Nomura

Koji Miyata

Yuhito Yoneda

Masaru Ito

Takehisa Minowa

Yuji Inoue

Dai Higuchi

Hideki Kobayashi

Hideo Kaneko

Satoshi Okazaki

Masataka Watanabe

Hiroaki Nagata

Toshiyuki Kikunaga

Masanobu Shimao

Ryo Osugi

Hideaki Kikuchi

Nobutaka Kobayashi

Masayuki Kawai

Kenichi Uesaka

Takeo Takada

Tetsuichi Chino

An anisotropic rare earth sintered magnet has a tetragonal RFeB compound as a major magnetic phase, wherein R is Nd or a mixture of Nd with at least one rare earth element. Grains of the compound phase have two crystallographic axes, c and a-axes aligned. The biaxially aligned magnet exhibits a coercivity Hc of at least 1.6 MA/m.

Anisotropic rare earth sintered magnet and making method

In a magnetic circuit for providing magnetic anisotropy in the in-plane radial direction of a soft magnetic under layer, magnets for perpendicular magnetization are respectively provide on the north and south poles of a magnet for horizontal magnetization. When magnetic circuits configured thus are stacked in a plurality of stages, a magnetic field (air-gap magnetic field) formed in a gap between the magnetic circuits is superimposed by magnetic fields from the magnets for perpendicular magnetization as well as a magnetic field from the magnet for horizontal magnetization (in-plane magnetization). The pole faces of the magnets for perpendicular magnetization are disposed closer to the gap between the magnetic circuits, so that a stronger magnetic field can be formed in the gap.

Magnetic circuit and method of applying magnetic field

In this invention, etching is not performed in the step of planarizing a polycrystalline Si wafer, but only mechanical grinding is performed for planarization. This is because, since the etching rate is crystal-face dependent, etching of the polycrystalline Si wafer unavoidably results in formation of steps due to different crystal face orientations of individual crystal grains exposed on a surface of the wafer, thus hindering precision surface planarization. Subsequently, the Si wafer surface is coated with an oxide film to form an Si wafer with oxide film prior to the final polishing stage and then a surface of the oxide film is planarized, to give a planar substrate (i.e., Si substrate with oxide film) having no step on the surface thereof.

Method of fabricating silicon substrate for magnetic recording media, and magnetic recording medium

It is an object of the present invention to provide a permanent magnet which is observed as a uniform structure without microstructures, but shows a pinning type initial magnetization curve. There is provided a rare earth permanent magnet comprising a magnetic intermetallic compound comprising R, T, N and an unavoidable impurity, wherein R is one or more rare earth elements comprising Y, T is two or more transition metal elements and comprises principally Fe and Co; wherein the magnetic intermetallic compound has an T/R atomic ratio of 6 to 14; a magnetocrystalline anisotropy energy of at least 1 MJ/m; a Curie point of at least 100&#xb0; C.; average particle diameter of at least 3 &#x3bc;m; and a substantially uniform structure; wherein the rare earth permanent magnet has a structure that gives a pinning-type initial magnetization curve; and wherein the magnetic intermetallic compound has a ThZn-type structure, and the like.

Rare earth permanent magnet

A bulk anisotropic rare earth permanent magnet consists essentially of R, Fe or Fe and Co, and N, wherein R is selected from rare earth elements inclusive of Y and contains Sm as a main component, and has a primary phase of ThZntype rhombohedral crystal structure, a density of at least 90% of the true density, and unidirectionally oriented C-axis. By electric conduction hot pressing of SmFeN base powder under rapid heating and rapid cooling conditions, the powder can be worked into the anisotropic bulk magnet without decomposing the 2-17 phase.

Bulk anisotropic rare earth permanent magnet and preparation method

The present invention provides a magnetron sputtering system, which ensures a formation of a desired thin film, using a thick target. In the sputtering process, a portion of the target does not have erosion free portions. The present invention provides a magnetron sputtering system comprising a chamber for sputtering, a target electrode installed inside said chamber, a substrate electrode installed in the chamber opposite to the target electrode, a ring-shaped magnet installed so as to enclose the side surface of the target electrode, and a semi-circular disk shaped magnet installed opposite to the target-mounted surface of the target electrode, wherein the semi-circular disk shaped magnet is rotated in the circumferential direction of the target electrode and is magnetized in the direction perpendicular to the target electrode. This ensures a specific magnetic field component to be generated over the thick planar target surface

Magnetron sputtering system and photomask blank production method based on the same

Disclosed is a rare earth-based sintered permanent magnet block used in the rotor of a permanent magnet synchronous motor. The magnet block of the form having an upper surface and a lower surface in parallel is provided in each of the upper and lower surfaces with at least one narrow slit having a specified incision depth, width and length so as to decrease the adverse influences of the eddy currents generated in the magnet block while the running direction of the slits in the upper surface and the running direction of the slits in the lower surface make an angle of at least 10&deg; or, preferably, 90&deg; so that the decrease in the bending strength of the magnet block due to the slits can be minimized without decreasing the desired eddy current-decreasing effect.

Rare earth-based sintered magnet and permanent magnet synchronous motor therewith

Disclosed is a magnetically anisotropic rare earth-based permanent magnet having a nanocomposite structure consisting of fine dispersion of a magnetically hard phase, e.g., Nd Fe B, in alignment relative to the easy magnetization axis, a magnetically soft phase and a non-magnetic phase having a melting point lower than those of the magnetically hard and soft phases. The permanent magnet is prepared in a process in which a quenched thin magnet alloy ribbon having a composition capable of forming a magnetically hard phase, magnetically soft phase and non-magnetic phase by a heat treatment is subjected to a heat treatment in a magnetic field of at least 3 T at a temperature not lower than the melting point of the non-magnetic phase so that the liquid phase formed from the non-magnetic phase serves to facilitate rotating orientation of the magnetically hard grains to be aligned in the direction of the magnetic field relative to the easy magnetization axis.

Anisotropic rare earth-based permanent magnet material

Disclosed is a method for the preparation of a magnetically anisotropic rare earth/iron/boron-based permanent magnet in a relatively bulky form having a nanocomposite structure as prepared from quenched thin ribbons of the alloy. The method comprises heating the powder of quenched thin ribbons to a temperature allowing partial formation of a liquid phase of a lanthanum/iron or rare earth/copper alloy of low melting point and subjecting the powder of the quenched thin ribbons to a uniaxial hot-deformation treatment by passing the powder under resistance heating through a gap between a pair of compression rollers.

Rare earth/iron/boron-based permanent magnet and method for the preparation thereof

Disclosed is a novel magnetically anisotropic rare earth-based permanent magnet having a nanocomposite structure consisting of a hard magnetic phase such as Nd,Fe,B and a soft magnetic phase such as bcc-iron, Fe,B and Fe,B in a volume ratio of 10:90 to 90:10 uniformly dispersed each in the other in a fineness of a few tens nanometers, in which particles of the hard magnetic phase are aligned in a direction relative to the easy magnetization axes of the particles. Such an anisotropic permanent magnet can be prepared by the method comprising: preparing a starting amorphous alloy of a composition susceptible to dispersion precipitation of the hard magnetic phase, for example, by the melt-spun method; forming the amorphous alloy into a magnet block; heating the magnet block at 600 to 1000&deg; C. to effect dispersion precipitation of the hard magnetic phase; and deforming the magnet block at the elevated temperature by compression unidirectionally so that the particles of the hard magnetic phase are aligned relative to the easy magnetization axes of the particles.

Magnetically anisotropic rare earth-based nanocomposite permanent magnet

Disclosed is a rare earth-based, magnetically anisotropic permanent magnet material consisting of a rare earth element, e.g., neodymium or praseodymium, iron optional in combination with cobalt and boron and having excellent magnetic properties by virtue of the magnetic coupling between the magnetically hard and soft phases. The magnet material has a structure consisting of crystalline particles of, e.g., Nd.sub.2 Fe.sub.14 B, having a particle diameter of 1 .mu.m or larger and fine crystals of iron of submicron size in a rod-shaped or platelet form precipitated within each crystalline particle of Nd.sub.2 Fe.sub.14 B. This magnet material can be prepared by several different methods including, for example, a solid phase reaction of an intermetallic compound of Nd.sub.2 Fe.sub.17 with boron to effect a double decomposition reaction producing Nd.sub.2 Fe.sub.14 B and iron.

Rare earth-based permanent magnet material and method for the

Disclosed is a novel composite magnet assembly for an insertion device of the Halbach type or hybrid type to be inserted into the linear part of, for example, an electron accelerator to generate a sine-curved periodical magnetic field in the air gap between two oppositely facing composite magnet block arrays. Different from a conventional magnet block assembly consisting of a plurality of permanent magnet blocks or alternate assembly of permanent magnet blocks and soft-magnetic pole pieces, the inventive magnet block assembly is composed of a plurality of oppositely facing composite magnet blocks each formed with a single base magnet block provided with a plurality of slits into which insert magnet pieces or insert pole pieces are inserted so that the dimensional accuracy in the length-wise direction of the magnet block assembly can be greatly decreased to improve the regularity of the periodical magnetic field. The base magnet block as well as the insert magnet piece in the Halbach type assembly can be magnetized after assemblage by the application of a pulsed magnetic field.

Magnet block assembly for insertion device

Provided by the invention is a method for the preparation of a magnetically anisotropic permanent magnet mainly consisting of crystallites of the Nd.sub.2 Fe.sub.14 B phase. The method comprises the steps of:(a) preparing an amorphous alloy of neodymium, iron and boron in molar fractions corresponding to the Nd.sub.2 Fe.sub.14 B phase or a nanocomposite of the Nd.sub.2 Fe.sub.14 B/Fe.sub.3 B or Nd.sub.2 Fe.sub.14 B/Fe system, for example, by the melt-spun method; and (b) subjecting the amorphous alloy of neodymium, iron and boron to a heat treatment in a magnetic field of at least 3 T (tesla) at a temperature in the range from 550 to 800.degree. C. for a length of time in the range from 1.times.10.sup.2 to 1.times.10.sup.4 seconds in an atmosphere of a non-reactive gas or vacuum.

Method for the preparation of rare earth based anisotropic permanent

Proposed is an improvement in an opposed-magnet magnetic circuit assembly with permanent magnets suitable for use, for example, in an MRI instrument comprising a pair of upper and lower permanent magnets to form a magnetic-field gap space therebetween, a pair of magnetic-field adjustment plates each on the surface of the permanent magnet to face the gap space and a pair of back yokes each on the back surface of the permanent magnet. According to the first aspect of the invention, a combination of a gradient coil and a shimming plate is mounted on the magnetic-field adjustment plate with intervention of several pieces of shim members and, further, another set of second shim members are bonded to the surface of the shimming plate facing the gap space with an object to improve the uniformity of the magnetic field in the gap space. According to the second aspect of the invention, which is directed to the problem of alleviation of the oppressive sense received by the patient lying in the MRI instrument due to his encaved condition, the back yokes are magnetically and mechanically connected with two and only two columnar connecting yokes each of which has a smaller cross section in the center portion than in the upper and lower end portions in order to ensure lateral openness on both sides of the patient. Preferable configurations are also proposed for the back yokes and the permanent magnets.

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Fukui, Japan

Ken Ohashi