Structural, mechanical and electronic properties of Nb2C: first-principles calculations. Issue 53 (3rd July 2017)

• Record Type: Journal Article
• Authors: Sha, Xiaojing; Xiao, Namin; Guan, Yongjun; Yi, Xiaosu
• Is Part Of: RSC advances. Volume 7:Issue 53(2017)
• Page Start: 33402
• Page End: 33407
• Publication Date: 2017-07-03
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c7ra05856j
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : By crystal structure search for Nb–C system, a P – x phase diagram was calculated and a new stable Nb2 C was predicted. The new phase is considered as a potential ultra-stiff and hard material. Abstract : Nb–C compounds are potential candidates to achieve high hardness and refractory nature. We performed a crystal structure search for the Nb–C system using an ab initio evolutionary algorithm implemented in the USPEX code. By comparing the formation enthalpy, a P – x phase diagram was calculated, and an orthorhombic Pnnm structure of Nb2 C was predicted and denoted as Nb2 C- I, which was both mechanically and dynamically stable. In this Pnnm phase, there are four-sided rings continuously along the c -axis, which probably contributes to the relatively high incompressibility of Nb2 C- I along the crystallographic c -axis. Moreover, the hardness and Young's modulus were calculated to be 28.5 GPa and 448.9 GPa, respectively; hence, the Nb2 C- I is considered as a potential ultra-stiff and hard material.