IRON NITRIDE MAGNETIC POWDER AND MAGNETIC RECORDING MEDIUM COMPRISING THE SAME

• US 20100035086A1
• Filed: 08/04/2009
• Published: 02/11/2010
• Est. Priority Date: 08/05/2008
• Status: Abandoned Application

• Current Assignee: Hitachi Maxell Limited (Maxell, Ltd.)
• Original Assignee: Hitachi Maxell Limited (Maxell, Ltd.)
• Inventors: SASAKI, Yuji, INOUE, Tetsutaro
• Application Number:
  US12/534,998
• Publication Number:
  US 20100035086A1
• Time in Patent Office: Days
• US Class Current: 428/811.200
• CPC Class Codes: G11B 5/70626 containing non-metallic substances
• CPC Class Codes: G11B 5/712 characterised by the surface treatment or coating of magnetic particles
• CPC Class Codes: G11B 5/714 characterised by the dimension of the magnetic particles
• CPC Class Codes: H01F 1/065 obtained by a reduction
• CPC Class Codes: Y10T 428/1121 Multilayer
• CPC Class Codes: Y10T 428/115 Magnetic layer composition

Abstract

A spherical or ellipsoidal iron nitride magnetic powder having a core comprising iron nitride including a Fe₁₆N₂ phase as a primary phase and an outer layer containing yttrium (Y) and aluminum (Al), in which an average particle size r of the iron nitride magnetic powder is 20 nm or less, an average diameter d of the core is 4 to 10 nm, and a ratio of r to d (r/d) is 2 to 3, and average content of yttrium and aluminum in the outer layer are from 0.9 to 5 atomic % and from 30 to 50 atomic %, respectively, each based on the total number of iron atoms in the iron nitride magnetic powder, and standard deviations of the contents of yttrium and aluminum are 0.6 atomic % or less and 17 atomic % or less, respectively.

Claims

1. A spherical or ellipsoidal iron nitride magnetic powder having a core comprising iron nitride including a Fe₁₆N₂ phase as a primary phase and an outer layer containing yttrium and aluminum,

wherein an average particle size r of the iron nitride magnetic powder is 20 nm or less, an average diameter d of the core is 4 to 10 nm, and a ratio of r to d (r/d) is 2 to 3, and

wherein an average content of yttrium in the outer layer is from 0.9 to 5 atomic % based on the total number of iron atoms in the iron nitride magnetic powder and a standard deviation of the content of yttrium is 0.6 atomic % or less, and an average content of aluminum is from 30 to 50 atomic % based on the total number of iron atoms in the iron nitride magnetic powder and a standard deviation of the content of aluminum is 17 atomic % or less, when elemental analyses are carried out at 10 points of the outer layer of each of 50 particles of the iron nitride magnetic powder by an X-ray analysis-transmission electron microscope.

2. A magnetic recording medium comprising a non-magnetic substrate and a magnetic layer containing an iron nitride magnetic powder according to claim 1 and a binder on said non-magnetic substrate.

3. The magnetic recording medium according to claim 2, which is utilized for a magnetic recording and reproduction system comprising a magnetoresistance effect device having a magnetoresistance ratio of at least 8% as a reproduction head.