Ferrimagnetic TiMn_1–<i>x</i>Os_2+<i>x</i>B₂ and TiNi_1–<i>x</i>Os_2+<i>x</i>B₂ Containing Chains of Mn₃‐ and Ni₃‐Triangles as Well as Trigonal Planar B₄ U

The novel quaternary borides TiM 1– x Os 2+ x B 2 (MMn, Ni; x ≈ 0.3) are synthesized via arc melting and characterized using powder and single‐crystal X‐ray diffraction (XRD), energy‐dispersive X‐ray analysis, and, for the MMn phase, SQUID magnetometry. Rietveld refinement of the powder XRD data reveals the presence of Os 1– x M x as a secondary phase in both products. Single‐crystal structure refinement indicates that Os atoms occupy two distinct crystallographic sites within the structure (Ti 1+ x Os 2– x RuB 2 ‐type, space group P 2 m , no. 189), while M (Mn, Ni) forms unprecedented chains of Mn 3 ‐ and Ni 3 ‐triangles, and boron atoms arrange into trigonal planar B 4 units. Magnetic susceptibility measurements of the MMn phase reveal a Curie temperature of ≈125 K and a negative Weiss constant of −173 K, suggestive of ferrimagnetic behavior. At low temperatures, a subtle peak in the susceptibility curve hints at a possible antiferromagnetic transition ( T N = 18 K). However, this low‐temperature magnetic ordering appears weak, as evidenced by a measurable hysteresis at 5 K with a coercivity of 36 kA m −1 , indicating mildly hard magnetic properties for this new phase.