The structural stability and electronic properties of N-doped and B-N-codoped cubic and hexagonal diamane (single-layer diamond) were investigated based on first-principles methods. The N atom tends to stay in the substitutional site rather than the interstitial site, and the most stable configuration is the structure where the N atom is located at the external substitutional site without H saturation. The B and N atoms codoped in diamane tend to gather to form a covalent bond, where N is saturated by H, since the stability of a lone pair of electrons in N is reduced by the B dopant. Moreover, B and N dopants can adjust the bandgap (0–3.52 eV) and reduce the formation energy (FE) of diamane to promote its synthesis. The formation energies of N-doped diamane are not sensitive to N distributions, and diamane containing a vertical B-N bond has the lowest FE due to the attraction between the N-dopant-induced electron and the B-dopant-induced hole.

The structural, electronic, and superconducting properties of B-doped cubic and hexagonal diamane (single layer diamond) were investigated based on the first-principles methods. B atom tends to stay in the substitutional site, and the most stable configuration is the structure with vertical B–B dimer. The formation energy of B-doped diamane is lower than the counterpart of pristine diamane indicating that B dopant can facilitate the synthesis of diamane. The configurations with vertical B–B dimers are semiconductors with tunable band gaps, which decrease with the B concentration increasing due to the interaction between B–B dimers. For example, the band gap of 3.125 mol% and 6.25 mol% B-doped cubic diamane is 1.82 eV and 1.44 eV, respectively. Moreover, configurations with meta-stable B distributions are metals, which have comparable superconducting transition temperatures with B-doped diamond (~4 K).

The exploration of the vast phase space of transition metal nitrides is critical for discovering novel materials and potential technological applications. Manganese mononitride with a tetragonal structure (space group I4/mmm) was synthesized in a laser-heating diamond anvil cell, which could be quenched to ambient pressure. The bulk modulus of 173 GPa was measured using in situ high-pressure diffraction, and the axial compressibility shows that, under pressure, the a direction is much more compressible than the c direction in tetragonal MnN. DFT results with correction of the on-site repulsion (GGA + U) confirm that tetragonal MnN is energetically stable and antiferromagnetic. This study highlights the need to include on-site repulsion to understand 3d metal nitrides.