Carbon network evolution from dimers to sheets in superconducting ytrrium dicarbide under pressure

Feng, Xiaolei and Lu, Siyu and Pickard, Chris J. and Liu, Hanyu and Redfern, Simon A. T. and Ma, Yanming (2018) Carbon network evolution from dimers to sheets in superconducting ytrrium dicarbide under pressure. Communications Chemistry, 1 (1). ISSN 2399-3669 DOI

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Carbon-bearing compounds display intriguing structural diversity, due to variations in hybrid bonding of carbon. Here, first-principles calculations and unbiased structure searches on yttrium dicarbide at pressure reveal four new structures with varying carbon polymerisation, in addition to the experimentally observed high-temperature low-pressure I4/mmm dimer phase. At low pressures, a metallic C2/m phase (four-member single-chain carbide) is stable, which transforms into a Pnma phase (single-chain carbide) upon increasing pressure, with further transformation to an Immm structure (double-chain carbide) at 54 GPa and then to a P6/mmm phase (sheet carbide) at 267 GPa. Yttrium dicarbide is structurally diverse, with carbon bonded as dimers (at lowest pressure), four-member single chains, infinite single chains, double chains and eventually sheet structures on compression. Electron–phonon coupling calculations indicate that the high-pressure phases are superconducting. Our results aid the understanding and design of new superconductors and illuminate pressure-induced carbon polymerisation in carbides.

Item Type: Article
Uncontrolled Keywords: 2018AREP; IA73
Subjects: 03 - Mineral Sciences
Divisions: 03 - Mineral Sciences
07 - Gold Open Access
Journal or Publication Title: Communications Chemistry
Volume: 1
Identification Number:
Depositing User: Sarah Humbert
Date Deposited: 23 Nov 2018 14:28
Last Modified: 23 Nov 2018 14:28

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