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New Ground-State Crystal Structure of Elemental Boron

An, Qi and Reddy, K. Madhav and Xie, Kelvin Y. and Hemker, Kevin J. and Goddard, William A., III (2016) New Ground-State Crystal Structure of Elemental Boron. Physical Review Letters, 117 (8). Art. No. 085501. ISSN 0031-9007. https://resolver.caltech.edu/CaltechAUTHORS:20160816-104402282

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Abstract

Elemental boron exhibits many polymorphs in nature based mostly on an icosahedral shell motif, involving stabilization of 13 strong multicenter intraicosahedral bonds. It is commonly accepted that the most thermodynamic stable structure of elemental boron at atmospheric pressure is the β rhombohedral boron (β−B). Surprisingly, using high-resolution transmission electron microscopy, we found that pure boron powder contains grains of two different types, the previously identified β−B containing a number of randomly spaced twins and what appears to be a fully transformed twinlike structure. This fully transformed structure, denoted here as τ−B, is based on the Cmcm orthorhombic space group. Quantum mechanics predicts that the newly identified τ−B structure is 13.8  meV/B more stable than β−B. The τ−B structure allows 6% more charge transfer from B_(57) units to nearby B_(12) units, making the net charge 6% closer to the ideal expected from Wade’s rules. Thus, we predict the τ−B structure to be the ground state structure for elemental boron at atmospheric pressure.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1103/PhysRevLett.117.085501DOIArticle
http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.117.085501PublisherArticle
http://journals.aps.org/prl/supplemental/10.1103/PhysRevLett.117.085501PublisherSupplemental Material
https://doi.org/10.1103/PhysRevLett.118.089602DOIReply to Discussion
ORCID:
AuthorORCID
An, Qi0000-0003-4838-6232
Goddard, William A., III0000-0003-0097-5716
Additional Information:© 2016 American Physical Society. Received 8 March 2016; revised manuscript received 27 May 2016; published 15 August 2016. QA and WAG were supported by the Defense Advanced Research Projects Agency (Grant No. W31P4Q-13-1-0010, program managers, John Paschkewitz), by the Army Research Laboratory under Cooperative Agreement No. W911NF-12-2-0022, and by the National Science Foundation (Grant No. DMR-1436985, program manager, John Schlueter). KMR, KYX and KH were supported by the Defense Advanced Research Projects Agency (Grant No. W31P4Q-13-1-0001). We gratefully acknowledge Professor Richard Haber and Dr. Chawon Hwang at Rutgers University, for coordinating our access to the commercial boron powders. We thank ARL for permission to use their HRTEM simulation facility. Q. A. and K. M. R. contributed equally to this work. Q. A., K. M. R., K. H., and W. A. G. wrote the Letter. K. M. R. performed the experimental measurements and image simulations including TEM and XRD, K. Y. X. contributed to the TEM, and Q. A. performed the quantum mechanics simulations. Q. A., K. M. R., K. Y. X., K. H., and W. A. G. analyzed the data and discussed the results. K. M. R. first observed the new structure before Q. A. performed the quantum mechanics simulations.
Funders:
Funding AgencyGrant Number
Defense Advanced Research Projects Agency (DARPA)W31P4Q-13-1-0010
Army Research LaboratoryW911NF-12-2-0022
NSFDMR-1436985
Defense Advanced Research Projects Agency (DARPA)W31P4Q-13-1-0001
Other Numbering System:
Other Numbering System NameOther Numbering System ID
WAG1179
Issue or Number:8
Record Number:CaltechAUTHORS:20160816-104402282
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20160816-104402282
Official Citation:New Ground-State Crystal Structure of Elemental Boron Qi An, K. Madhav Reddy, Kelvin Y. Xie, Kevin J. Hemker, and William A. Goddard, III Phys. Rev. Lett. 117, 085501
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:69660
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:16 Aug 2016 17:58
Last Modified:03 Oct 2019 10:24

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