Pressure-induced reconstructive phase transitions, polarization with metallicity, and enhanced hardness in antiperovskite MgCNi3. Issue 33 (17th August 2021)

• Record Type: Journal Article
• Authors: Cui, Yingqi; Cheng, Hao; Tian, Hao; Li, Chenggang; Tang, Yanan; Mao, Ai-Jie; Kuang, Xiao-Yu
• Is Part Of: Physical chemistry chemical physics. Volume 23:Issue 33(2021)
• Page Start: 18221
• Page End: 18226
• Publication Date: 2021-08-17
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/d1cp02742e
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : Pressure induces two novel phases in MgCNi3 . One is a polar metal phase and the other possesses an enhanced hardness stemming from a robust s–s electrons interaction. Abstract : In general, hydrostatic pressure can suppress electrical polarization, instead of creating and/or enhancing polarization like strain engineering. Here, a combination of first-principles calculations and CALYPSO crystal structures prediction is used to point out that hydrostatic pressure applied on antiperovskite MgCNi3 can stabilize polarization with metallicity, and thus a polar metal can exist under high pressure. Strikingly, the metallic polar phase of MgCNi3 exhibits an original linear–cubic coupling between polar and nonpolar modes, resulting in an asymmetrical double-well when the polarization is switched. Moreover, another novel phase of MgCNi3 under high pressure possesses an enhanced hardness stemming from a robust s–s electrons interaction of an unexpected C–C bond, rather than typical sp 3 orbital hybridization. These discoveries open new routes to design superhard materials and polar metals.