Ferrite sintered magnet

Patent metadata

Field	Value
Publication number	US-11456096-B2
Application number	US-201916267400-A
Country	US
Kind code	B2
Filing date	Feb 5, 2019
Priority date	Mar 28, 2018
Publication date	Sep 27, 2022
Grant date	Sep 27, 2022

Abstract

There is provided a ferrite sintered magnet having a high residual magnetic flux density.A ferrite sintered magnet 2 includes a plurality of main phase particles 5 including ferrite having a hexagonal structure, the number of core-shell structured particles 5A having a core 7 and a shell 9 covering the core 7, among the main phase particles 5, is smaller than the number of the main phase particles 5 other than the core-shell structured particles 5A.

First claim

What is claimed is:

1. A ferrite sintered magnet comprising a plurality of main phase particles including ferrite having a hexagonal structure,
wherein some of the main phase particles are core-shell structured particles having a core and a shell covering the core,
a number of the core-shell structured particles is smaller than a number of the main phase particles other than the core-shell structured particles.

2. The ferrite sintered magnet according to claim 1 , wherein a unit of a content of Sr is at. %, and
a content of Sr in the core is higher than a content of Sr in the shell.

3. The ferrite sintered magnet according to claim 1 , wherein a unit of a content of Ca is at. %, and
a content of Ca in the shell is higher than a content of Ca in the core.

4. The ferrite sintered magnet according to claim 1 , wherein a unit of a content of Sr is at. %,
a unit of a content of Ca is at. %, and
a content of Sr in the core is higher than a content of Ca in the core.

5. The ferrite sintered magnet according to claim 1 , wherein a unit of a content of Sr is at. %,
a unit of a content of Ca is at. %, and
a content of Ca in the shell is higher than a content of Sr in the shell.

6. The ferrite sintered magnet according to claim 1 , wherein at least a part of a metal component included in the ferrite sintered magnet is represented by Formula (1) below:
Ca 1-w-x-y R w Sr x Ba y Fe z Co m   (1),

wherein R in Formula (1) is at least one element selected from the group consisting of rare earth elements and Bi, R includes at least La,
w, x, y, z, and m in Formula (1) satisfy Formulae (2), (3), (4), (5), (6), (7), (8), and (9) below:
0.25< w< 0.5  (2);

0.01< x< 0.35  (3);

0≤ y< 0.013  (4);

y<x   (5);

8.5< z< 9.9  (6);

1.0< w/m< 2.1  (7);

0.017< m/z< 0.055  (8); and

0<1- w - x - y< 1  (9), and

the ferrite sintered magnet includes a Si component.

7. The ferrite sintered magnet according to claim 6 , wherein w, x, and m in the Formula (1) satisfy Formulae (2a), (3a), and (10) below:
0.350< w< 0.420,  (2a);

0.120< x< 0.180,  (3a); and

0.200< m< 0.280,  (10); and

the content of B in the ferrite sintered magnet is 0.037 to 0.181 mass % in terms of H 3 BO 3 .

8. The ferrite sintered magnet according to of claim 1 , wherein a content of Al in the ferrite sintered magnet is 0.05 to 0.3 mass % in terms of Al 2 O 3 .

9. The ferrite sintered magnet according to claim 1 , wherein a ratio of a number of the core-shell structured particles to a total number of the main phase particles is more than 0% and less than 50%.

Assignees

• Tdk Corp

Inventors

• Morita Hiroyuki
• Ikeda Masanori
• Murakawa Yoshitaka
• Murase Taku

Classifications

• C04B2235/6562

  Heating rate · CPC title

• C04B2235/3274

  Ferrites · CPC title

• H01F41/026

  protecting methods against environmental influences, e.g. oxygen, by surface treatment (magnetic particles with skin H01F1/061, H01F1/09, H01F1/24, H01F1/33 and G11B5/706) · CPC title

• C04B2235/3227

  Lanthanum oxide or oxide-forming salts thereof · CPC title

• H01F1/11

  in the form of particles {(for magnetic record carriers G11B5/70626)} · CPC title