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Ductility in Crystalline Boron Subphosphide (B_(12)P_2) for Large Strain Indentation

An, Qi and Goddard, William A., III (2017) Ductility in Crystalline Boron Subphosphide (B_(12)P_2) for Large Strain Indentation. Journal of Physical Chemistry C, 121 (30). pp. 16644-16649. ISSN 1932-7447. doi:10.1021/acs.jpcc.7b05429.

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Our studies of brittle fracture in B_4C showed that shear-induced cracking of the (B_(11)C) icosahedra leading to amorphous B_4C regions induced cavitation and failure. This suggested that to obtain hard boron-rich phases that are ductile, we need to replace the CBC chains of B_4C with two-atom chains that can migrate between icosahedra during shear without cracking the icosahedra. We report here a quantum mechanism (QM) simulation showing that under indentation stress conditions, superhard boron subphosphide (B_(12)P_2) displays such a unique deformation mechanism. Thus, stress accumulated as shear increases is released by slip of the icosahedra planes through breaking and then reforming the P–P chain bonds without fracturing the (B_(12)) icosahedra. This icosahedral slip may facilitate formation of mobile dislocation and deformation twinning in B_(12)P_2 under high-stress conditions, leading to high ductility. However, the presence of twin boundaries (TBs) in B_(12)P_2 will weaken the icosahedra along TBs, leading to the fracture of (B_(12)) icosahedra under indentation stress conditions. These results suggest that crystalline B_(12)P_2 is an ideal superhard material to achieve high ductility.

Item Type:Article
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URLURL TypeDescription Information
An, Qi0000-0003-4838-6232
Goddard, William A., III0000-0003-0097-5716
Alternate Title:Ductility in Crystalline Boron Subphosphide (B12P2) for Large Strain Indentation
Additional Information:© 2017 American Chemical Society. Received: June 2, 2017; Revised: July 5, 2017; Published: July 11, 2017. This work was initiated with support by the National Science Foundation (DMR-1436985, program manager, John Schlueter). It was completed with support by the Defense Advanced Research Projects Agency (W31P4Q-13-1-0010 and W31P4Q-12-1-0008, program manager, John Paschkewitz) Q.A. was also supported by the Army Research Laboratory under Cooperative Agreement Number W911NF-12-2-0022 and by the U. S. Nuclear Regulatory Commission (NRC-HQ-84-15-G-0028). The authors declare no competing financial interest.
Funding AgencyGrant Number
Defense Advanced Research Projects Agency (DARPA)W31P4Q-13-1-0010
Defense Advanced Research Projects Agency (DARPA)W31P4Q-12-1-0008
Army Research LaboratoryW911NF-12-2-0022
Nuclear Regulatory CommissionNRC-HQ-84-15-G-0028
Issue or Number:30
Record Number:CaltechAUTHORS:20170712-073553748
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Official Citation:Ductility in Crystalline Boron Subphosphide (B12P2) for Large Strain Indentation Qi An and William A. Goddard, III The Journal of Physical Chemistry C 2017 121 (30), 16644-16649 DOI: 10.1021/acs.jpcc.7b05429
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:78979
Deposited By: Tony Diaz
Deposited On:12 Jul 2017 17:10
Last Modified:15 Nov 2021 17:44

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