CommunicationPrediction on technetium triboride from first-principles calculations

•We report the first-principles prediction on technetium triboride (TcB3).•The predicted hexagonal P6¯m2 structure TcB3 is a hard material (HV=29 GPa).•The TcB3 (No.187) is mechanically, dynamically, and thermodynamically stable.•The TcB3 (No.187) can be synthesized under pressures above 4 GPa.

Taking the Tc-B binary system as an example, here we report the first-principles prediction on new phases of technetium borides, TcB3, which has an unprecedented stoichiometry. Crystal structures, phase stability, electronic properties and mechanical properties of TcB3 have been investigated using first-principles calculations. The hexagonal P6¯m2 structure (No.187) TcB3 with a high value of hardness (29 GPa) is energetically stable against decomposition into other compounds under pressures above 4 GPa, indicating that TcB3 can be synthesized above this pressure.