The recent theoretical prediction of a new compound, WB₅, has spurred the interest in tungsten borides and their possible implementation in industry. In this research, the experimental synthesis and structural description of a boron‐rich tungsten boride and measurements of its mechanical properties are performed. 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 WB_5−x. Previously incorrectly referred to as “WB₄,” it is distinct from earlier theoretically suggested WB₄, a phase with a different crystal structure that has not yet been synthesized and is predicted to be thermodynamically stable at pressures above 1 GPa. Mild synthesis conditions (enabling a scalable synthesis) and excellent mechanical properties make WB_5−x a very promising material for drilling technology.

Fluorescence spectra of nanodiamonds synthesized at high pressure from adamantane and other organic compounds show narrow (≈1 nm) lines of unknown origin over the spectroscopic range from ≈500 to 800 nm. The study proposes and experimentally confirms the hypothesis that these lines are related to radiative recombination of donor–acceptor pairs (DAP). According to the experimental data, these pairs can be formed from donor‐like substitutional nitrogen present in the diamond lattice and 2D acceptor layer resulting from the effect of transfer doping on the nanodiamond surface. A peculiar behavior of the narrow lines is identified within the temperature range of 100–10 K: their energy position slightly shifts downward, and the majority of the lines divide into two or more components as the temperature decreases. The lines are shown to be predominantly associated with single photon emitters, with an emission rate exceeding 1 million counts s ⁻¹ at room temperature. A new narrowband source of room‐temperature fluorescence found in hydrogen‐terminated nanodiamonds push horizons for quantum optical technologies related to the development of single photon emitters and temperature nanosensors.

Boron-doped diamonds were synthesized by the reaction of an amorphous globular carbon powder (80%) with a powder of 1,7-di (oxymethyl)-M-carborane (20%) in a ‘toroid’-type high-pressure chamber at a pressure of 8.0 GPa and temperature of 1700 °C. The structure was refined by the Rietveld method according to the X-ray powder diffraction data. It was shown that the unit cell parameters of these diamonds have two discrete quantities: around 3.570 Å for small concentrations of B (~1–1.5%) and around 3.578 Å for large concentrations of B (~2–3%). The concentration of the vacancies in the diamonds exceeds the concentration of boron atoms by 2–3 fold. This fact can play an important role in the formation of the structure and in determining the physical properties of diamonds.

Superhard composites with ultrafine grain were obtained at pressures of about 8.0 GPa from pyrolytic graphite, boron nitride, and graphite-like B-C-N-phases. A homogeneous structure is formed throughout the volume of samples or dominant martensitic transformation of the hexagonal lattice. Activators of the phase transition cause the growth of particles of cubic phases by diffusion recrystallization.