Prediction the structure, mechanical properties and melting point of<scp>D8<sub>m</sub>‐Mo<sub>5</sub>SiB<sub>2</sub></scp>and<scp><i>Cmcm</i>‐Mo<sub>5</sub>SiB<sub>2</sub></scp>
Delin Pu, Yong Pan
Abstract
Abstract Mo 5 SiB 2 is an ideal candidate for high temperature material. Although the D8 l ‐Mo 5 SiB 2 has been published, the other phases and the related properties of Mo 5 SiB 2 are still unclear. Here, two possible Mo 5 SiB 2 phases (D8 m ‐Mo 5 SiB 2 and Cmcm ‐Mo 5 SiB 2 ) are predicted by using the first principles method. The structural stability, mechanical properties, melting point and electronic structure of Mo 5 SiB 2 are studied. The results show that the D8 m ‐Mo 5 SiB 2 and Cmcm ‐Mo 5 SiB 2 are thermodynamically and dynamically stables. The calculated bulk elastic modulus, shear modulus and Young's modulus of the Cmcm ‐Mo 5 SiB 2 are close to D8 l ‐Mo 5 SiB 2 . In addition, the predicted Cmcm ‐Mo 5 SiB 2 has high melting point (2518.5°C) compared to the D8 l ‐Mo 5 SiB 2 and D8 m ‐Mo 5 SiB 2 . In particular, the predicted D8 m ‐Mo 5 SiB 2 exhibits better plasticity than the D8 l ‐Mo 5 SiB 2 . The calculated density of states and Mulliken overlap population shows that the D8 m ‐Mo 5 SiB 2 and Cmcm ‐Mo 5 SiB 2 all exhibit metallic behavior. The metallic behavior mainly depends on the electronic interaction between Mo atom and B atom near Fermi level. Furthermore, the bond length of Mo‐B bond in the D8 m ‐Mo 5 SiB 2 is longer than the other two structures, which may be the reason why the ductility of the former is better than the latter.