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The ternary TaIr2B2 boride was prepared by the reaction between iridium and TaB2 powders. It was shown that a choice in favor of any crystal structure of TaIr2B2 boride using only X-ray powder diffraction analysis and single-crystal XRD is rather difficult to make. The DFT calculations were carried out to predict the energetically preferred crystal structure of TaIr2B2. The 11B solid-state NMR spectrum of TaIr2B2 was recorded for the first time. A combination of diffraction and spectroscopic methods, as well as theoretical calculations, allowed us to make clear choice in favor of the triclinic space group for the crystal structure of TaIr2B2. The Vickers microhardness value for TaIr2B2 was found to be 17.9 ± 2.3 GPa, and the ternary TaIr2B2 boride can be considered a hard material. Therefore, the family of hard ternary boride phases got a new member. The coefficients of thermal expansion of TaIr2B2 measured by in situ high-temperature XRD analysis are independent of temperature along the a and b axes, but the CTE along the c axis deviates noticeably at elevated temperatures. The findings for the new ternary TaIr2B2 boride are of interest for the rational design of complex structural materials containing Ta–Ir–B-based components and prediction of their high-temperature behavior. Further research into this ternary boride as well as other iridium-containing ternary borides will provide a tool to solve the problems faced by high-temperature materials science. [ABSTRACT FROM AUTHOR]

We have studied the thermal expansion of CaIr4B4, IrB1.1, and CaB6. The results demonstrate that the crystal lattices of these phases expand linearly with temperature and that their thermal expansion coefficients lie in the range (5–10) × 10–6 K–1. We have determined the average microhardness of the CaIr4B4, IrB1.1, and CaB6 phases. The average microhardness of the CaIr4B4 phase is ~15 GPa, which is a factor of 3 lower than that of the CaB6 phase. [ABSTRACT FROM AUTHOR]