Ferrite sintered magnet

Patent metadata

Field	Value
Publication number	US-11488752-B2
Application number	US-202017026848-A
Country	US
Kind code	B2
Filing date	Sep 21, 2020
Priority date	Sep 25, 2019
Publication date	Nov 1, 2022
Grant date	Nov 1, 2022

Abstract

The present invention provides a ferrite sintered magnet comprising ferrite crystal grains having a hexagonal structure, wherein the ferrite sintered magnet comprises metallic elements at an atomic ratio represented by formula (1). In formula (1), R is at least one element selected from the group consisting of Bi and rare-earth elements, and R comprises at least La. In formula (1), w, x, z and m satisfy formulae (2) to (5). The above-mentioned ferrite sintered magnet further has a coefficient of variation of a size of the crystal grains in a section parallel to a c axis of less than 45%.

Ca 1-w-x R w Sr x Fe z Co m   (1)

0.360≤ w ≤0.420  (2)

0.110≤ x ≤0.173  (3)

8.51≤ z ≤9.71  (4)

0.208≤ m ≤0.269  (5)

First claim

What is claimed is:

1. A ferrite sintered magnet comprising ferrite crystal grains having a hexagonal structure,
wherein the ferrite sintered magnet comprises metallic elements at an atomic ratio represented by formula (1):
Ca 1-w-x R w Sr x Fe z Co m   (1) and

wherein R is at least one element selected from the group consisting of Bi and rare-earth elements,
R comprises at least La,
w, x, z and m satisfy formulae (2) to (5):
0.360≤ w≤ 0.420  (2)

0.110≤ x≤ 0.173  (3)

8.51≤ z≤ 9.71  (4)

0.208≤ m≤ 0.269  (5)

and a coefficient of variation of a size of the crystal grains in a section parallel to a c axis is less than 45%.

2. The ferrite sintered magnet according to claim 1 , wherein the ferrite sintered magnet further comprises 0.037 to 0.181% by mass of B in terms of H 3 BO 3 .

3. The ferrite sintered magnet according to claim 1 , wherein the ferrite sintered magnet further comprises 0.03 to 0.3% by mass of Al in terms of Al 2 O 3 .

4. The ferrite sintered magnet according to claim 1 , wherein the ferrite sintered magnet further comprises 0.001 to 0.068% by mass of Ba in terms of BaO.

Assignees

• Tdk Corp

Inventors

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

Classifications

• C04B2235/3298

  Bismuth oxides, bismuthates or oxide forming salts thereof, e.g. zinc bismuthate · CPC title

• H01F1/11 Primary

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

• C04B35/6262

  of calcined, sintered clinker or ceramics · CPC title

• C04B2235/3227

  Lanthanum oxide or oxide-forming salts thereof · CPC title

• C04B2235/3217

  Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina · CPC title