A new hard phase and physical properties of Tc2C predicted from first principles. Issue 70 (12th July 2016)

• Record Type: Journal Article
• Authors: Zhang, Gangtai; Zhao, Yaru; Bai, Tingting; Wei, Qun; Yuan, Yuquan
• Is Part Of: RSC advances. Volume 6:Issue 70(2016)
• Page Start: 66066
• Page End: 66073
• Publication Date: 2016-07-12
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c6ra11786d
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : Using the first principles particle swarm optimization algorithm for crystal structural prediction, we have predicted a hexagonal P 63 / mmc structure of Tc2 C. Abstract : Using the first principles particle swarm optimization algorithm for crystal structural prediction, we have predicted a hexagonal P 63 / mmc structure of Tc2 C. The new phase is mechanically and dynamically stable, as verified by its elastic constants and phonon dispersion. The formation enthalpy–pressure curves show that the predicted P 63 / mmc -Tc2 C is more energetically favorable than the previously proposed Mo2 C-, anti -MoS2 -, Re2 P-, and Fe2 N-type structures in the considered pressure range. The calculated mechanical properties show that it is an ultra-incompressible and hard material. Meanwhile, the directional dependences of the Young's modulus, bulk modulus, and shear modulus for Tc2 C are systematically investigated. The analyses of the density of states and electronic localization function reveal the presence of strong covalent bonding between Tc and C atoms, which is of crucial importance in forming a hard material.