Synthesis, Crystal Structure, and Compressibilities of Mn$_{3−x}$Ir$_5$B$_{2+x}$ $(0 ≤ x ≤ 0.5)$ and Mn$_2$IrB$_2$

Abstract

The new ternary transition metal borides Mn$_{3‐x}$Ir$_5$B$_{2+x}$ (0≤x≤0.5) and Mn$_2$IrB$_2$ were synthesized from the elements under high temperature and high‐pressure/high‐temperature conditions. Both phases can be synthesized as powder samples in a radio‐frequency furnace in argon atmosphere. High‐pressure/high‐temperature conditions were used to grow single‐crystals. The phases represent the first ternary compounds within the system Mn–Ir–B. Mn$_{3−x}$Ir$_5$B$_{2+x}$ (0≤x≤0.5) crystallizes in the Ti$_3$Co$_5$B$_2$ structure type (P4/mbm; no. 127) with parameters a=9.332(1), c=2.896(2) Å, and Z=2. Mn$_2$IrB$_2$ crystallizes in the β‐Cr$_2$IrB$_2$ crystal structure type (Cmcm; no. 63) with parameters a=3.135(3), b=9.859(5), c=13.220(3) Å, and Z=8. The compositions of both compounds were confirmed by EDX measurements and the compressibility was determined experimentally for Mn$_{3−x}$Ir$_5$B$_{2+x}$ and by DFT calculations for Mn$_2$IrB$_2$