HIP synthesis of η-carbide-type nitrides Fe3W3N and Fe6W6N and their magnetic properties

Abstract We have succeeded in synthesising iron–tungsten nitrides using the hot isostatic pressing (HIP) method and have measured their magnetic properties. Two η-carbide-type iron–tungsten nitrides with lattice constants a  = 11.043(1) and 10.937(2) A were synthesised directly from metal elements under high-pressure nitrogen gas. Their compositions are expected to be Fe 3 W 3 N and Fe 6 W 6 N in analogy with other η-carbide-type compounds. Fe 3 W 3 N is a ferromagnet with a Curie temperature T C  = 110 K and a saturation moment P S  = 0.78 μ B /Fe, whereas Fe 6 W 6 N is an antiferromagnet with a Neel temperature T N  = 75 K and shows a metamagnetic transition at around 25 T.