Hexagonal ferrite magnetic powder and magnetic recording medium

Patent metadata

Field	Value
Publication number	US-9251832-B2
Application number	US-201414223139-A
Country	US
Kind code	B2
Filing date	Mar 24, 2014
Priority date	Mar 25, 2013
Publication date	Feb 2, 2016
Grant date	Feb 2, 2016

Abstract

An aspect of the present invention relates to hexagonal ferrite magnetic powder, which has an activation volume ranging from 900 nm 3 to 1,600 nm 3 , and a ratio of a coefficient of plate thickness variation to a coefficient of particle diameter variation, coefficient of plate thickness variation/coefficient of particle diameter coefficient, ranging from 0.20 to 0.60.

First claim

What is claimed is:

1. Hexagonal barium ferrite magnetic powder, which has:
an activation volume ranging from 900 nm 3 to 1,600 nm 3 , and
a ratio of a coefficient of plate thickness variation to a coefficient of particle diameter variation, coefficient of plate thickness variation/coefficient of particle diameter variation, ranging from 0.40 to 0.60.

2. The hexagonal barium ferrite magnetic powder according to claim 1 , which has a coercive force ranging from 195 kA/m to 400 kA/m.

3. The hexagonal barium ferrite magnetic powder according to claim 1 , which exhibits a switching field distribution, SFD, ranging from 0.2 to 0.8.

4. The hexagonal barium ferrite magnetic powder according to claim 2 , which exhibits a switching field distribution, SFD, ranging from 0.2 to 0.8.

5. The hexagonal barium ferrite magnetic powder according to claim 1 , which has a specific surface area ranging from 80 m 2 /g to 150 m 2 /g.

6. The hexagonal barium ferrite magnetic powder according to claim 2 , which has a specific surface area ranging from 80 m 2 /g to 150 m 2 /g.

7. The hexagonal barium ferrite magnetic powder according to claim 3 , which has a specific surface area ranging from 80 m 2 /g to 150 m 2 /g.

8. The hexagonal barium ferrite magnetic powder according to claim 1 , wherein the content of rare earth elements relative to Fe ranges from 0 atomic percent to 0.1 atomic percent.

9. The hexagonal barium ferrite magnetic powder according to claim 2 , wherein the content of rare earth elements relative to Fe ranges from 0 atomic percent to 0.1 atomic percent.

10. The hexagonal barium ferrite magnetic powder according to claim 3 , wherein the content of rare earth elements relative to Fe ranges from 0 atomic percent to 0.1 atomic percent.

11. The hexagonal barium ferrite magnetic powder according to claim 1 , which comprises 1.5 atomic percent to 20 atomic percent of Al relative to Fe.

12. The hexagonal barium ferrite magnetic powder according to claim 2 , which comprises 1.5 atomic percent to 20 atomic percent of Al relative to Fe.

13. The hexagonal barium ferrite magnetic powder according to claim 3 , which comprises 1.5 atomic percent to 20 atomic percent of Al relative to Fe.

14. The hexagonal barium ferrite magnetic powder according to claim 8 , which comprises 1.5 atomic percent to 20 atomic percent of Al relative to Fe.

15. The hexagonal barium ferrite magnetic powder according to claim 1 , which is magnetic powder for magnetic recording.

16. A magnetic recording medium comprising a magnetic layer comprising ferromagnetic powder and binder on a nonmagnetic support, wherein the ferromagnetic powder is the hexagonal barium ferrite magnetic powder according to claim 1 .

Assignees

• Fujifilm Corp

Inventors

• Suzuki Hiroyuki
• Tada Toshio

Classifications

• H01F1/11

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

• G11B5/70678 Primary

  Ferrites · CPC title

• Y10T428/2982

  Particulate matter [e.g., sphere, flake, etc.] · CPC title