Tungsten pentaboride WB5-x

Tungsten pentaboride (WB_5-x) is a unique material possessing a number of exciting physical and chemical properties

Optimization of synthesis in collaboration with Tomsk Polytechnic University (Inorg. Chem. 2022, 61, 18, 6773–6784)
Followed by the previous achievements we proposed an efficient method toward the synthesis of higher tungsten boride WB_5–x in the vacuumless direct current atmospheric arc discharge plasma. The crystal structure of the synthesized samples of boron-rich tungsten boride was determined using computational techniques, showing a two-phase system. We determined the optimal parameters of synthesis to obtain samples with 61.5% WB_5–x by volume. Our study shows the possibility of using the proposed vacuumless method as an efficient and inexpensive way to synthesize superhard WB_5–x without employing resource-consuming vacuum techniques

Experimental synthesis in collaboration with IHPP RAS and Gazpromneft STC (Adv. Sci. 2020, 7, 2000775)
Our theoretical prediction of a new compound, WB₅, has spurred the interest in tungsten borides and their possible implementation in industry.
The ab initio calculations of the structural energies corresponding to different local structures make it possible to formulate the rules determining the likely local motifs in the disordered versions of the WB₅ structure, all of which involve boron deficit. The generated disordered WB_4.18 and WB_4.86 models both perfectly match the experimental data, but the former is the most energetically preferable. The precise crystal structure, elastic constants, hardness, and fracture toughness of this phase are calculated, and these results agree with the experimental findings. Because of the compositional and structural similarity with predicted WB₅, this phase is denoted as WB₅₋_x.

Theoretical prediction (J. Phys. Chem. Lett. 2018, 9, 12, 3470–3477)
Tungsten pentaboride material, more precisely, its ideal stoichiometric counterpart was firstly predicted in 2018 by using evolutionary crystal structure prediction algorithm USPEX.
New boron-rich compound WB₅ is predicted to be superhard, with a Vickers hardness of 45 GPa, to possess high fracture toughness of ∼4 MPa·m^0.5, and to be thermodynamically stable in a wide range of temperatures at ambient pressure.