In Np Fe 2 the easy axis is ⟨111⟩. Above T C ≈ 500 K, NpFe 2 is also paramagnetic and cubic. Cooling below the Curie temperature produces a rhombohedral distortion wherein the rhombohedral angle changes from 60° (cubic phase) to 60.53°. An alternate description of this distortion is to consider the length c along the unique trigonal axis (after the distortion has begun) and a as the distance in the plane perpendicular to c. In the cubic phase this reduces to c / a = 1.00. Below the Curie temperature