Carbon-rich superhard ruthenium carbides from first-principles. (5th March 2017)

• Record Type: Journal Article
• Authors: Zhao, Shipeng; Yang, Yali; Lu, Jian; Wu, Wei; Sun, Sheng; Li, Xi; Zhao, Xinluo; Cao, Shixun; Zhang, Jincang; Ren, Wei
• Is Part Of: Materials & design. Volume 117(2017)
• Page Start: 353
• Page End: 362
• Publication Date: 2017-03-05
• Subjects: First-principles calculations -- Dynamical stabilities -- Mechanical properties; Materials -- Periodicals; Engineering design -- Periodicals; Matériaux -- Périodiques; Conception technique -- Périodiques; Electronic journals; 620.11
• DOI: 10.1016/j.matdes.2016.12.094
• Languages: English
• ISSNs: 0264-1275

Abstract

Abstract: Compounds formed by transition metals and light elements have attracted increasing attention owing to superior functionalities. Here, high throughput first-principles calculations are employed to investigate the crystal structures and physical properties of ruthenium carbides with various stoichiometries. It is found that the R 3 ¯ m -Ru2 C, R 3 ¯ m -RuC, P 3 ¯ m 1-Ru2 C3, P 3 ¯ m 1-RuC2, P 3 ¯ m 1-RuC3 and C 2 /c -RuC4 are the ground states for the respective chemical compositions at ambient pressure, from a systematical investigation of both thermodynamic and mechanical stabilities, as well as phonon dispersions. Further calculations indicate that P 3 ¯ m 1-RuC3 and P 63 / mmc- RuC4 are ultra-incompressible with high bulk and shear modulus. Subsequent empirical calculations predict that the carbon-rich P 3 ¯ m 1-RuC3 and P 63 / mmc- RuC4 are superhard materials with a large Vickers hardness of 45.1 GPa and 41.5 GPa, respectively. In addition, a strong covalent CC bonding was observed from the electronic localization function contours of all the ground states, which is crucial for their excellent mechanical properties. Graphical abstract: Highlights: Ruthenium carbides with various stoichiometries were studied by density functional theory calculations. Ground states of Ru2 C, RuC, Ru2 C3, RuC2, RuC3 and RuC4 are found, pressure-induced phase transitions are uncovered. Two carbon-rich structures are found to have large Vickers hardness 45.1 GPa and 41.5 GPa.