First-principles investigations of the structure and physical properties for new TcN crystal structure. (17th June 2016)

• Record Type: Journal Article
• Authors: Zhao, Ya-Ru; Zhang, Gang-Tai; Yan, Hai-Yan; Bai, Ting-Ting; Zheng, Bao-Bing; Yuan, Yu-Quan
• Is Part Of: Molecular physics. Volume 114:Number 12(2016)
• Page Start: 1952
• Page End: 1959
• Publication Date: 2016-06-17
• Subjects: Structure prediction -- first-principles calculations -- TcN -- thermodynamic properties; Molecules -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Molécules -- Périodiques; Chimie physique et théorique -- Périodiques; 539.6.05
• DOI: 10.1080/00268976.2016.1171407
• Languages: English
• ISSNs: 0026-8976

Abstract

ABSTRACT: Using a newly developed particle swarm optimisation technique on crystal structural prediction, we have predicted an orthorhombic Imm 2 structure for TcN crystal, which is energetically much superior to the previously proposed NbO-type and R -3 m structures. The new phase is stable against decomposition into the mixture of Tc and N at ambient condition. The stability is confirmed by the subsequent calculations on the phonon dispersion curves and elastic constants. An analysis of the mechanical properties indicates that Imm 2-TcN is incompressible and common hard material. The evidence of strong covalent bonding of Tc-N, which plays a leading role to form a hard material, is manifested by the partial densities of state analysis. In addition, the thermodynamic properties, such as Debye temperature, heat capacity, thermal expansion coefficient, and Grüneisen parameter of TcN are investigated by the quasi-harmonic Debye model. Abstract :