Hexagonal ferrite magnetic powder for magnetic recording, method for producing hexagonal ferrite magnetic particles, and magnetic recording medium

• US 9,748,026 B2
• Filed: 12/23/2015
• Issued: 08/29/2017
• Est. Priority Date: 06/28/2013
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: Shirata, Masashi
• Primary Examiner(s): BERNATZ, KEVIN M
• Application Number:
  US14/757,517
• Publication Number:
  US 20160141084A1
• Time in Patent Office: 615 Days
• Field of Search: None
• CPC Class Codes: G11B 5/70678 Ferrites
• CPC Class Codes: H01F 1/11 in the form of particles for magnetic record carriers G11B5/70626

Abstract

Provided are hexagonal ferrite magnetic powder for magnetic recording, being comprised of hexagonal ferrite magnetic particles having a crystalline metal oxide adhered to a surface thereof, a method for producing hexagonal ferrite magnetic particles having a crystalline metal oxide adhered to a surface thereof, and a magnetic recording medium.

Claims

1. Hexagonal ferrite magnetic powder for magnetic recording, which is comprised of hexagonal ferrite magnetic particles having a crystalline metal oxide adhered to a surface thereof,

wherein the activation volume is in a range of 800 nm³ to 1600 nm³, and the crystalline metal oxide is a crystalline oxide of a metal selected from the group consisting of Al, Zr, and Ce.

2. The hexagonal ferrite magnetic powder for magnetic recording according to claim 1,

wherein the hexagonal ferrite magnetic particles are hexagonal ferrite magnetic particles having a crystalline metal oxide adhered to the surface thereof in which the amount of the metal falls within a range of 0.5 atom % to 20 atom % with respect to 100 atom % of Fe.

3. The hexagonal ferrite magnetic powder for magnetic recording according to claim 1,

wherein the hexagonal ferrite magnetic particles are barium ferrite magnetic particles.

4. The hexagonal ferrite magnetic powder for magnetic recording according to claim 1,

wherein the hexagonal ferrite magnetic particles are strontium ferrite magnetic particles.

5. A magnetic recording medium having a magnetic layer including ferromagnetic powder and a binder on a non-magnetic support body,

wherein the ferromagnetic powder is hexagonal ferrite magnetic powder for magnetic recording, which is comprised of hexagonal ferrite magnetic particles having a crystalline metal oxide adhered to a surface thereof,

the hexagonal ferrite magnetic powder for magnetic recording has an activation volume in a range of 800 nm³ to 1600 nm³, and

the crystalline metal oxide is a crystalline oxide of a metal selected from the group consisting of Al, Zr, and Ce.

6. The magnetic recording medium according to claim 5,

wherein the hexagonal ferrite magnetic particles are hexagonal ferrite magnetic particles having a crystalline metal oxide adhered to the surface thereof in which the amount of the metal falls within a range of 0.5 atom % to 20 atom % with respect to 100 atom % of Fe.

7. The magnetic recording medium according to claim 5,

wherein the hexagonal ferrite magnetic particles are barium ferrite magnetic particles.

8. The magnetic recording medium according to claim 5,

wherein the hexagonal ferrite magnetic particles are strontium ferrite magnetic particles.