By combining first-principles calculations with the particle swarm optimization algorithm, we predicted a hexagonal Pˉ3m1 structure for Tc B, which is energetically more favorable than the previously reported WC-type...By combining first-principles calculations with the particle swarm optimization algorithm, we predicted a hexagonal Pˉ3m1 structure for Tc B, which is energetically more favorable than the previously reported WC-type and Cmcm structures.The new phase is mechanically and dynamically stable, as confirmed by its phonon and elastic constants calculations.The calculated mechanical properties show that it is an ultra-incompressible and hard material. Meanwhile, the elastic anisotropy is investigated by the shear anisotropic factors and ratio of the directional bulk modulus. Density of states analysis reveals that the strong covalent bonding between Tc and B atoms plays a leading role in forming a hard material. Additionally, the compressibility, bulk modulus, Debye temperature, Gruneisen parameter, specific heat, and thermal expansion coefficient of Tc B are also successfully obtained by using the quasi-harmonic Debye model.展开更多
基金Project supported by the Science Foundation of Baoji University of Arts and Sciences of China(Grant No.ZK11061)the Natural Science Foundation of the Education Committee of Shaanxi Province,China(Grant Nos.2013JK0637,2013JK0638,and 2014JK1044)
文摘By combining first-principles calculations with the particle swarm optimization algorithm, we predicted a hexagonal Pˉ3m1 structure for Tc B, which is energetically more favorable than the previously reported WC-type and Cmcm structures.The new phase is mechanically and dynamically stable, as confirmed by its phonon and elastic constants calculations.The calculated mechanical properties show that it is an ultra-incompressible and hard material. Meanwhile, the elastic anisotropy is investigated by the shear anisotropic factors and ratio of the directional bulk modulus. Density of states analysis reveals that the strong covalent bonding between Tc and B atoms plays a leading role in forming a hard material. Additionally, the compressibility, bulk modulus, Debye temperature, Gruneisen parameter, specific heat, and thermal expansion coefficient of Tc B are also successfully obtained by using the quasi-harmonic Debye model.
