Novel superhard B-C-O phases predicted from first principles

We explored the B-C-O system at pressures in the range 0-50 GPa by ab initio variable-composition evolutionary simulations in the hope of discovering new stable superhard materials. A new tetragonal thermodynamically stable phase B 4 CO 4 , space group I 4&cmb.macr;, and two low-enthalpy metasta...

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Published in:Physical chemistry chemical physics : PCCP 2016-01, Vol.18 (3), p.1859-1863
Main Authors: Wang, Shengnan, Oganov, Artem R, Qian, Guangrui, Zhu, Qiang, Dong, Huafeng, Dong, Xiao, Davari Esfahani, M. Mahdi
Format: Article
Language:English
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Summary:We explored the B-C-O system at pressures in the range 0-50 GPa by ab initio variable-composition evolutionary simulations in the hope of discovering new stable superhard materials. A new tetragonal thermodynamically stable phase B 4 CO 4 , space group I 4&cmb.macr;, and two low-enthalpy metastable compounds (B 6 C 2 O 5 , B 2 CO 2 ) have been discovered. Computed phonons and elastic constants show that these structures are dynamically and mechanically stable both at high pressure and zero pressure. B 4 CO 4 is thermodynamically stable at pressures above 23 GPa, but should remain metastable under ambient conditions. Its computed hardness is about 38-41 GPa, which suggests that B 4 CO 4 is potentially superhard. Structure of B 4 CO 4 . The purple, black and red balls are boron, carbon and oxygen atoms, respectively.
ISSN:1463-9076
1463-9084
DOI:10.1039/c5cp05367f