Tdk Corporation

Eiichiro Fukuchi

Taku Murase

Masashi Ito

Kenya Takagawa

Kenichi Suzuki

Ryuji Hashimoto

Yuki Nagamine

Fumitaka Baba

Akira Kakinuma

Shogo Kadota

To provide a rare earth permanent magnet having as a main phase a compound with a NdFecrystalline structure having strong coercive force. A rare earth permanent magnet having as a main phase a compound with a NdFecrystalline structure, wherein when the composition ratio of the rare earth permanent magnet is expressed as RTC, where R is one or more rare earth elements requiring Sm, and T is one or more transition metal elements requiring Fe or Fe and Co, a and b satisfy 18&#x3c;a&#x3c;40 and 0.5&#x2264;b, and a phase where R and C are denser than the main phase is provided in the grain boundary phase of the rare earth permanent magnet.

Rare-earth permanent magnet

A rare earth permanent magnet that is high in residual magnetization and coercivity is obtained and includes R and T. A main phase of crystal grains having an NdFetype crystal structure is included. In an X-ray diffraction profile drawn by performing an XRD measurement for a rare earth permanent magnet, peaks of detected intensity are present in specific ranges. In which the detected intensity of the peak with the highest detected intensity in the range of 41.60&#xb0;&#x3c;2&#x3b8;(&#xb0;)&#x3c;42.80&#xb0; is set as &#x3b1;, the detected intensity of the peak with the highest detected intensity in the range of 34.38&#xb0;&#x3c;2&#x3b8;(&#xb0;)&#x3c;34.64&#xb0; is set as &#x3b2;, and the detected intensity of the peak with the highest detected intensity in the range of 38.70&#xb0;&#x3c;2&#x3b8;(&#xb0;)&#x3c;41.20&#xb0; is set as &#x3b3;, 0.38&#x3c;&#x3b1;/&#x3b2;&#x3c;0.70 and 0.45&#x3c;&#x3b3;/&#x3b2;&#x3c;0.70 are established. The peak with the highest detected intensity in the range of 34.38&#xb0;&#x3c;2&#x3b8;(&#xb0;)&#x3c;34.64&#xb0; is a peak derived from the NdFetype crystal structure.

Rare earth permanent magnet

A permanent magnet having a periodic structure with the concentrations of Fe and T (T is one or more transition metal elements with Co or Ni as necessity) changing alternately, wherein, the concentrations change with a period of 3.3 nm or less and the concentration difference of Fe in the concentration change is 5 at % or more. The permanent magnet has a high saturation magnetization Is and coercivity HcJ and can be prepared even without rare earth element(s) R.

Permanent magnet and rotating machine including the same

The present invention provides a production method of a ferrite material comprising as main constituents FeO: 62 to 68 mol %, ZnO: 12 to 20 mol %, and MnO substantially constituting the balance, wherein the method comprises a compacting step for obtaining a compacted body by using a powder containing the main constituents, the powder having a specific surface area falling within a range between 2.5 and 5.0 m/g and a 90% particle size of 10 &#x3bc;m or less, and a sintering step for sintering the compacted body obtained in the compacting step. Accordingly, the saturation magnetic flux density of the Mn&#x2014;Zn based ferrite can be improved.

Method for producing ferrite material and ferrite material

The present invention provides a Mn&#x2014;Zn ferrite which is low in the loss in the frequency range between a few 10 kHz and a few 100 kHz and high in the saturation magnetic flux density in the vicinity of 100&#xb0; C. The present invention comprising the steps of compacting a powder having a specific surface area (based on the BET method) of 2.0 to 5.0 m/g and a 50% particle size of 0.7 to 2.0 &#x3bc;m into a compacted body having a predetermined shape and obtaining a sintered body by sintering the compacted body. It is preferable that a Mn&#x2014;Zn ferrite comprises, as main constituents, 54 to 57 mol % of FeO, 5 to 10 mol % of ZnO, 4 mol % or less (not inclusive of 0%) of NiO, and the balance substantially being MnO.

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Tokyo, Japan

Eiichiro Fukuchi