Magnetic, Electronic, and Mechanical Properties of Bulk ε-Fe₂N Synthesized at High Pressures

We sintered bulk trigonal ε-Fe₂N (space group: P312) with the high-pressure and high-temperature method. Structural refinements by the Rietveld method result in a trigonal unit cell with parameters of a = 4.7767(1) Å and c = 4.4179(3) Å. ε-Fe₂N is ferromagnetic with a Curie temperature of ∼250 K, a saturation magnetization (M _s) value of up to 1.2 μ_B/formula units (f.u.), and comparatively low coercive field. The Vickers hardness was measured, and the results showed that the asymptotic hardness of bulk ε-Fe₂N is about 6.5 GPa with a load of 1000 g. Thermogravimetric (TG) analysis shows that ε-Fe₂N is thermally stable below 670 K. ε-Fe₂N exhibits good metal conductivity, and the electron transport measurements show that the resistivity of it is 172 μΩ cm at room temperature. The theoretical calculations suggest that the conducting states are mainly derive from Fe-3d states.