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Prediction of a new ground state of superhard compound B6O at ambient conditions.

ABSTRACT: Boron suboxide B6O, the hardest known oxide, has an Rm crystal structure (?-B6O) that can be described as an oxygen-stuffed structure of ?-boron, or, equivalently, as a cubic close packing of B12 icosahedra with two oxygen atoms occupying all octahedral voids in it. Here we show a new ground state of this compound at ambient conditions, Cmcm-B6O (?-B6O), which in all quantum-mechanical treatments that we tested comes out to be slightly but consistently more stable. Increasing pressure and temperature further stabilizes it with respect to the known ?-B6O structure. ?-B6O also has a slightly higher hardness and may be synthesized using different experimental protocols. We suggest that ?-B6O is present in mixture with ?-B6O, and its presence accounts for previously unexplained bands in the experimental Raman spectrum.

SUBMITTER: Dong H

PROVIDER: S-EPMC4976382 | biostudies-literature | 2016 Aug

REPOSITORIES: biostudies-literature

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Prediction of a new ground state of superhard compound B6O at ambient conditions.

Dong Huafeng H Oganov Artem R AR Wang Qinggao Q Wang Sheng-Nan SN Wang Zhenhai Z Zhang Jin J Esfahani M Mahdi Davari MM Zhou Xiang-Feng XF Wu Fugen F Zhu Qiang Q

Scientific reports 20160808

Boron suboxide B6O, the hardest known oxide, has an Rm crystal structure (α-B6O) that can be described as an oxygen-stuffed structure of α-boron, or, equivalently, as a cubic close packing of B12 icosahedra with two oxygen atoms occupying all octahedral voids in it. Here we show a new ground state of this compound at ambient conditions, Cmcm-B6O (β-B6O), which in all quantum-mechanical treatments that we tested comes out to be slightly but consistently more stable. Increasing pressure and temper ...[more]

PMID: 27498718

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