Structure refinements of iron borides Fe2B and FeB

Crystals of the iron borides FeB and Fe2B were obtained from two different high temperature synthesis routes, viz. in combined copper/gallium flux and under high pressure conditions. Their crystal structures were investigated at room and low temperatures. Structure models from the literature were confirmed. The position of the boron atoms was unambiguously determined. FeB (Pnma, no. 62) contains zig-zag chains of boron atoms in which the boron atoms are coordinated by seven iron atoms in the form of a mono-capped trigonal prism. Fe2B (I4/mcm, no. 140) contains single boron atoms in a square antiprismatic iron atom coordination.