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Superhard Boron-Rich Boron Carbide with Controlled Degree of Crystallinity

Department of Physics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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Materials 2020, 13(16), 3622; https://doi.org/10.3390/ma13163622
Received: 8 July 2020 / Revised: 11 August 2020 / Accepted: 13 August 2020 / Published: 16 August 2020
(This article belongs to the Section Thin Films and Interfaces)
Superhard boron-rich boron carbide coatings were deposited on silicon substrates by microwave plasma chemical vapor deposition (MPCVD) under controlled conditions, which led to either a disordered or crystalline structure, as measured by X-ray diffraction. The control of either disordered or crystalline structures was achieved solely by the choice of the sample being placed either directly on top of the sample holder or within an inset of the sample holder, respectively. The carbon content in the B-C bonded disordered and crystalline coatings was 6.1 at.% and 4.5 at.%, respectively, as measured by X-ray photoelectron spectroscopy. X-ray diffraction analysis of the crystalline coating provided a good match with a B50C2-type structure in which two carbon atoms replaced boron in the α-tetragonal B52 structure, or in which the carbon atoms occupied different interstitial sites. Density functional theory predictions were used to evaluate the dynamical stability of the potential B50C2 structural forms and were consistent with the measurements. The measured nanoindentation hardness of the coatings was as high as 64 GPa, well above the 40 GPa threshold for superhardness. View Full-Text
Keywords: ceramics/coating materials; chemical synthesis; vapor deposition; mechanical properties; crystal structure; computer simulation ceramics/coating materials; chemical synthesis; vapor deposition; mechanical properties; crystal structure; computer simulation
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MDPI and ACS Style

Chakrabarty, K.; Chen, W.-C.; Baker, P.A.; Vijayan, V.M.; Chen, C.-C.; Catledge, S.A. Superhard Boron-Rich Boron Carbide with Controlled Degree of Crystallinity. Materials 2020, 13, 3622. https://doi.org/10.3390/ma13163622

AMA Style

Chakrabarty K, Chen W-C, Baker PA, Vijayan VM, Chen C-C, Catledge SA. Superhard Boron-Rich Boron Carbide with Controlled Degree of Crystallinity. Materials. 2020; 13(16):3622. https://doi.org/10.3390/ma13163622

Chicago/Turabian Style

Chakrabarty, Kallol, Wei-Chih Chen, Paul A. Baker, Vineeth M. Vijayan, Cheng-Chien Chen, and Shane A. Catledge. 2020. "Superhard Boron-Rich Boron Carbide with Controlled Degree of Crystallinity" Materials 13, no. 16: 3622. https://doi.org/10.3390/ma13163622

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