Samarium-iron-nitrogen alloy powder and method for producing same
AssigneesNational Institute of Advanced Industrial Science and Technology, TDK Corporation
InventorsShusuke Okada, Kazuyuki Suzuki, Kenta Takagi, Kimihiro Ozaki, Yasushi Enokido
Life of this patent
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Abstract
A samarium-iron-nitrogen alloy powder according to one embodiment of the present invention is characterized in that a value obtained by dividing the hydrogen content of the samarium-iron-nitrogen alloy powder by the BET specific surface area of the samarium-iron-nitrogen alloy powder is less than or equal to 400 ppm/(m2/g), and a value obtained by dividing the oxygen content of the samarium-iron-nitrogen alloy powder by the BET specific surface area of the samarium-iron-nitrogen alloy powder is less than or equal to 11,000 ppm/(m2/g).
Claims7
A samarium-iron-nitrogen alloy powder characterized in that:
- a value obtained by dividing a hydrogen content of the samarium-iron-nitrogen alloy powder by a BET specific surface area of the samarium-iron-nitrogen alloy powder is in a range of from 200 ppm/m2/g) to 400 ppm/(m2/g);
- a value obtained by dividing an oxygen content of the samarium-iron-nitrogen alloy powder by the BET specific surface area of the samarium-iron-nitrogen alloy powder is less than or equal to 11,000 ppm/(m2/g);
- an average particle diameter of the samarium-iron-nitrogen alloy powder is less than or equal to 1 μm;
- and
- a coercivity of the samarium-iron-nitrogen alloy powder is at least 18 kOe when the average particle diameter is 1 μm and the coercivity increases as the average particle diameter decreases from 1 μm, to 0.63 μm.
A method for producing a samarium-iron-nitrogen alloy powder having an average particle diameter of less than or equal to 1 μm, the method comprising:
- performing a reduction-diffusion process on a samarium-iron alloy precursor powder to produce a samarium-iron alloy powder;
- nitriding the samarium-iron alloy powder;
- washing the nitrided samarium-iron alloy powder with a solvent capable of dissolving calcium;
- and
- dehydrogenating the washed powder to produce the samarium-iron-nitrogen alloy powder such that a value obtained by dividing a hydrogen content of the samarium-iron-nitrogen alloy powder by a BET specific surface area of the samarium-iron-nitrogen alloy powder is in a range of from 200 ppm/(m2/g) to 400 ppm/(m2/g), and a value obtained by dividing an oxygen content of the samarium-iron-nitrogen alloy powder by the BET specific surface area of the samarium-iron-nitrogen alloy powder is less than or equal to 11,000 ppm/(m2/g);
- wherein the reduction-diffusion process step, the nitriding step, the washing step, and the dehydrogenating step are carried out in a non-oxidizing atmosphere, and the samarium-iron-nitrogen alloy powder has a coercivity of at least 18 kOe when the average particle diameter is 1 μm and the coercivity increases as the average particle diameter decreases from 1 μm to 0.63 μm.
Dependencies are inferred from the claim text.