Ferrite sintered magnet

Patent metadata

Field	Value
Publication number	US-11476023-B2
Application number	US-202117207085-A
Country	US
Kind code	B2
Filing date	Mar 19, 2021
Priority date	Mar 23, 2020
Publication date	Oct 18, 2022
Grant date	Oct 18, 2022

Abstract

A ferrite sintered magnet including ferrite grains having a hexagonal crystal structure. The ferrite grains satisfy 0.56≤W≤0.68 where W is an average value of circularities of the ferrite grains in a cross section parallel to an axis of easy magnetization.

First claim

What is claimed is:

1. A ferrite sintered magnet comprising ferrite grains having a hexagonal crystal structure, wherein
the ferrite grains satisfy 0.56≤W≤0.68
where W is an average value of circularities of the ferrite grains in a cross section parallel to an axis of easy magnetization.

2. The ferrite sintered magnet according to claim 1 , wherein
an average value of Heywood diameters of the ferrite grains in the cross section is 1.00 μm or more and 1.23 μm or less.

3. The ferrite sintered magnet according to claim 1 comprising 0.010 mass % or more and 0.090 mass % or less of Mg in terms of MgO.

4. The ferrite sintered magnet according to claim 1 comprising Ca, R, A, Fe and Co in an atomic ratio of Ca 1-w-x R w A x Fe z Co m , wherein
R includes La only or includes La and at least one selected from rare earth elements,
A is at least one selected from Ba and Sr,
0.364≤w≤0.495,
0.038≤x≤0.136,
8.280≤z≤10.45 and
0.257≤m≤0.338.

5. The ferrite sintered magnet according to claim 1 , comprising Ca, R, A, Fe and Co, wherein
R includes La only or includes La and at least one selected from rare earth elements,
A is at least one selected from Ba and Sr,
Ca is 2.505 mass % or more and 2.951 mass % or less in terms of CaO,
R is 8.028 mass % or more and 8.239 mass % or less in terms of R 2 O 3 ,
A is 0.666 mass % or more and 1.666 mass % or less in terms of AO,
Fe is 84.564 mass % or more and 84.937 mass % or less in terms of Fe 2 O 3 , and
Co is 2.341 mass % or more and 2.521 mass % or less in terms of CoO.

6. The ferrite sintered magnet according to claim 1 , comprising 0.005 mass % or more and 0.058 mass % or less of B in terms of B 2 O 3 .

Assignees

• Tdk Corp

Inventors

• Ikeda Masanori
• Morita Hiroyuki
• Murakawa Yoshitaka
• Muroya Shogo

Classifications

• C04B2235/3262

  Manganese oxides, manganates, rhenium oxides or oxide-forming salts thereof, e.g. MnO · CPC title

• C01P2004/61

  Micrometer sized, i.e. from 1-100 micrometer · CPC title

• C04B35/2633

  containing barium, strontium or calcium · CPC title

• C04B35/62645

  Thermal treatment of powders or mixtures thereof other than sintering · CPC title

• C01P2006/10

  Solid density · CPC title