Magnetic metal power and method of producing the powder

Abstract

A magnetic metal powder having fluidity is provided which is composed of FePt nanoparticles synthesized by the polyol synthesis method that possess fct (face-centered tetragonal) structure and exhibit crystal magnetic anisotropy from immediately after synthesis. Specifically, there is provided a magnetic metal powder having fluidity which is composed of magnetic metal particles whose main components and the contents thereof are represented by the following general formula (1): [T X M 1−X ] Y Z 1−Y   (1), where T is one or both of Fe and Co, M is one or both of Pt and Pd, Z is at least one member selected from the group composed of Ag, Cu, Bi, Sb, Pb and Sn, X represents 0.3˜0.7, and Y represents 0.7˜1.0, the balance being impurities unavoidably incorporated during production, which magnetic metal powder has a volumetric ratio of ferromagnetic structure (face-centered tetragonal ratio) as measured by Mossbauer spectroscopy in the range of 10˜100%, saturation magnetization σs of 20 emu/g or greater, and average primary particle diameter by transmission electron microscopic observation (TEM) of 30 nm or less.

1 - 7 . (canceled) 
     
     
         8 . A magnetic metal powder having fluidity such that the powder is free flowing, the free flowing magnetic powder having uniaxial crystal magnetic anisotropy as produced without heat treatment and being composed of magnetic metal particles whose main components and the contents thereof are represented by the following general formula (1):
   [T X M 1−X ] Y Z 1−Y   (1),   where T is one or both of Fe and Co, M is one or both of Pt and Pd, Z is at least one member selected from the group composed of Ag, Cu, Bi, Sb, Pb and Sn, X represents 0.3˜0.7, and Y represents 0.7˜1.0, the balance being impurities unavoidably incorporated during production,   which magnetic metal powder has a volumetric ratio of ferromagnetic structure (face-centered tetragonal ratio) as measured by Mossbauer spectroscopy in the range of 10˜100%, saturation magnetization σs of 20 emu/g or greater, and average primary particle diameter by transmission electron microscopic observation (TEM) of 30 nm or less.   
     
     
         9 . A magnetic metal powder according to  claim 8 , which has a magnetic anisotropy Hk by magnetic torque measurement of 10.0 kOe or greater. 
     
     
         10 . A magnetic metal powder according to  claim 8 , which has an average primary particle diameter of 20 nm or less. 
     
     
         11 . The powder of  claim 8 , wherein said fluidity permits the powder to rotate freely when the powders are positioned in and subjected to a magnetic field.