Triangular Arrangement of Ferromagnetic Iron Chains in the High-T Ferromagnet TiFe Os B.

Transition-metal borides (TMBs) containing B -fragment (n>3) have recently gained interest for their ability to enable exciting magnetic materials. Herein, we show that the B -containing TiFe Os B is a new ferromagnetic TMB with a Curie temperature of 523(2) K and a Weiss constant of 554(3) K, originating from the chain of M -triangles (M=64 %Fe+36 %Os). The new phase was synthesized from the elements by arc-melting, and its structure was elucidated by single-crystal X-ray diffraction. It belongs to the Ti Os RuB -type structure (space group P 2 m, no. 189) and contains trigonal-planar B boron fragments [B-B distance of 1.87(4) Å] interacting with M -triangles [M-M distances of 2.637(8) Å and 3.0199(2) Å]. The experimental results were supported by computational calculations based on the ideal TiFeOs B composition, which revealed strong ferromagnetic interactions within and between the Fe -triangles. This discovery represents the first magnetically ordered Os-rich TMB, thus it will help expand our knowledge of the role of Os in low-dimensional magnetism of intermetallics and enable the design of such materials in the future.