Abstract
Submicron-sized Sm2Fe17 powder samples were fabricated by a non-pulverizing process through reduction-diffusion of precursors prepared by a wet-chemical technique. Three precursors having different morphologies, which were micron-sized porous Sm-Fe oxide-impregnated iron nitrate, acicular goethite impregnated-samarium nitrate, and a conventional Sm-Fe coprecipitate, were prepared and subjected to hydrogen reduction and reduction-diffusion treatment to clarify whether these precursors could be convert to Sm2Fe17 without impurity phases and which precursor is the most attractive for producing submicron-sized Sm2Fe17 powder. As a result, all three precursors were successfully converted to Sm2Fe17 powders without impurity phases, and the synthesis route using iron-oxide particle-impregnated samarium oxide was revealed to have the greatest potential among the three routes.
Highlights
Submicron-sized Sm2Fe17 powder samples were fabricated by a non-pulverizing process through reduction-diffusion of precursors prepared by a wet-chemical technique
All three precursors were successfully converted to Sm2Fe17 powders without impurity phases, and the synthesis route using iron-oxide particle-impregnated samarium oxide was revealed to have the greatest potential among the three routes
Sm2Fe17N3 is an promising alternative to the Nd,Dy-Fe-B magnets used in motors exposed to high temperature, since it has high magnification comparable to Nd2Fe14B, with a huge anisotropy field and high Curie temperature
Summary
Sm2Fe17N3 is an promising alternative to the Nd,Dy-Fe-B magnets used in motors exposed to high temperature, since it has high magnification comparable to Nd2Fe14B, with a huge anisotropy field and high Curie temperature. In spite of the huge anisotropy of 260 kOe, the coercivity of current Sm2Fe17N3 fine powders is only around 10-15 kOe, and required improvement. It is known that particle size reduction results in higher coercivity in Sm2Fe17N3.1 The authors believe that coercivity is influenced by differences in the methods used to produce Sm2Fe17N3 fine powder. The coercivity of fine (3 μm) Sm2Fe17N3 powder produced directly through reduction-diffusion of Sm-Fe precursors prepared by a wet-chemical technique (direct synthesis method) showed higher coercivity (13 kOe)[2] than powder with a size of about 2 μm prepared by pulverizing coarse Sm2Fe17N3 powder (11 kOe).[3] Pulverized particles are thought to have strain and edges which form reverse magnetic domain nucleation sites and thereby reduce coercivity. Sm2Fe17 powders were successfully prepared, and the differences among the production routes were demonstrated
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