Ground-state structures, physical properties and phase diagram of carbon-rich nitride C5N. (31st August 2018)

• Record Type: Journal Article
• Authors: Wu, Qinghua; Hu, Qianku; Hou, Yiming; Wang, Haiyan; Zhou, Aiguo; Wang, Libo
• Is Part Of: Journal of physics. Volume 30:Number 38(2018)
• Publication Date: 2018-08-31
• Subjects: carbon nitride -- phase transition -- first-principles calculations -- superhard -- phase diagram; Condensed matter -- Periodicals; Matière condensée -- Périodiques; Vaste stoffen; Vloeistoffen; Natuurkunde; Electronic journals; Computer network resources; 530.4105
• DOI: 10.1088/1361-648X/aada2c
• Languages: English
• ISSNs: 0953-8984

Abstract

Abstract: Using the ab initio evolutionary algorithm, four thermodynamically stable C5 N phases (, -1, -2 and C2/m ) are uncovered. The structures of the, -1 and -2 phases possess layered features. The dense C2/m phase with 3D strong covalent bond network is calculated to be superhard with hardness of 75.4 and 83.9 GPa by Chen and Gao models. The electronic properties of the C5 N is diverse including conductor ( ), indirect semiconductor ( -1 and -2) and direct semiconductor ( C2/m ). Pressure-induced phase transition sequences and critical pressure points are calculated to be → -1 → -2 at 2.7 and 34 GPa, respectively. Though the C2/m phase is metastable at zero temperature, our established pressure-temperature phase diagram of C5 N shows that the C2/m becomes stable under high temperatures and pressures. The pressure-temperature phase diagram will give theoretical guidance for further experimental synthesis of different C5 N phases.