α鉄のアンモニア窒化による窒化鉄Fe_xN(x : 2, 2-3, 4, 16/2)の合成とFe_<16>N_2バルク試料の磁性 Synthesis of Iron Nitrides Fe_xN(x : 2, 2-3, 4, 16/2)by Nitrogenizing α-Fe in Ammonia Gas, and Magnetic Properties of The Bulk Sample of Fe_<16>N_2
Iron nitrides were prepared by nitrogenizing α-iron in ammonia gas at temperatures from 100°C to 700°C. In the case using iron foils as a starting material, Fe<SUB>2-3</SUB>N and Fe<SUB>4</SUB>N were formed as a main crystal phase at the temperature ranges of 450-700°C and 250-400°C, respectively. A crystal phase like to Fe<SUB>16</SUB>N<SUB>2</SUB> was formed at 210°C, but its XRD and Mössbauer data were too insufficient to identify as Fe<SUB>16</SUB>N<SUB>2</SUB>. While bulk Fe<SUB>16</SUB>N<SUB>2</SUB> was formed by nitrogenizing iron fine powder with the diameter of about 20nm at 110°C for 10days, but small amounts of Fe<SUB>3</SUB>N coexisted as a second phase with Fe<SUB>16</SUB>N<SUB>2</SUB> at 120°C for 10days. Crystal structure of Fe<SUB>16</SUB>N<SUB>2</SUB> was refined by Rietveld method. The average magnetic moment of three kinds of Fe atoms in Fe<SUB>16</SUB>N<SUB>2</SUB> was evaluated to be 2.52μB on the basis of its Mossbauer data, the value of which was larger by 15% than the magnetic moment of α-Fe. The saturation magnetization of the Fe<SUB>16</SUB>N<SUB>2</SUB> powder was also larger by about 14% than that of the α-Fe powder before nitrogenizing.
粉体および粉末冶金 46(2), 151-155, 1999-02-15
Japan Society of Powder and Powder Metallurgy