Received 9 May 2011; revised 7 July 2011; Accepted 8 July 2011. Available online 20 July 2011.
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) Å were synthesised directly from metal elements under high-pressure nitrogen gas. Their compositions are expected to be Fe3W3N and Fe6W6N in analogy with other η-carbide-type compounds. Fe3W3N is a ferromagnet with a Curie temperature TC = 110 K and a saturation moment PS = 0.78μB/Fe, whereas Fe6W6N is an antiferromagnet with a Néel temperature TN = 75 K and shows a metamagnetic transition at around 25 T.