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) 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.