Computational Predictions and Microwave Plasma Synthesis of Superhard Boron-Carbon Materials

Superhard boron-carbon materials are of prime interest due to their non-oxidizing properties at high temperatures compared to diamond-based materials and their non-reactivity with ferrous metals under extreme conditions. In this work, evolutionary algorithms combined with density functional theory h...

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Main Authors:	Paul A. Baker, Shane A. Catledge, Sumner B. Harris, Kathryn J. Ham, Wei-Chih Chen, Cheng-Chien Chen, Yogesh K. Vohra
Format:	Article
Language:	English
Published:	MDPI AG 2018-07-01
Series:	Materials
Subjects:	boron-carbon compound superhard materials ab initio calculations chemical vapor deposition
Online Access:	http://www.mdpi.com/1996-1944/11/8/1279

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spelling	doaj-art-60c1732926b94545bd7010473ac5c2822018-08-22T07:57:10ZengMDPI AGMaterials1996-19442018-07-01118127910.3390/ma11081279ma11081279Computational Predictions and Microwave Plasma Synthesis of Superhard Boron-Carbon MaterialsPaul A. Baker0Shane A. Catledge1Sumner B. Harris2Kathryn J. Ham3Wei-Chih Chen4Cheng-Chien Chen5Yogesh K. Vohra6Department of Physics, University of Alabama at Birmingham (UAB), Birmingham, AL 35294, USADepartment of Physics, University of Alabama at Birmingham (UAB), Birmingham, AL 35294, USADepartment of Physics, University of Alabama at Birmingham (UAB), Birmingham, AL 35294, USADepartment of Physics, University of Alabama at Birmingham (UAB), Birmingham, AL 35294, USADepartment of Physics, University of Alabama at Birmingham (UAB), Birmingham, AL 35294, USADepartment of Physics, University of Alabama at Birmingham (UAB), Birmingham, AL 35294, USADepartment of Physics, University of Alabama at Birmingham (UAB), Birmingham, AL 35294, USASuperhard boron-carbon materials are of prime interest due to their non-oxidizing properties at high temperatures compared to diamond-based materials and their non-reactivity with ferrous metals under extreme conditions. In this work, evolutionary algorithms combined with density functional theory have been utilized to predict stable structures and properties for the boron-carbon system, including the elusive superhard BC5 compound. We report on the microwave plasma chemical vapor deposition on a silicon substrate of a series of composite materials containing amorphous boron-doped graphitic carbon, boron-doped diamond, and a cubic hard-phase with a boron-content as high as 7.7 at%. The nanoindentation hardness of these composite materials can be tailored from 8 GPa to as high as 62 GPa depending on the growth conditions. These materials have been characterized by electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, X-ray diffraction, and nanoindentation hardness, and the experimental results are compared with theoretical predictions. Our studies show that a significant amount of boron up to 7.7 at% can be accommodated in the cubic phase of diamond and its phonon modes and mechanical properties can be accurately modeled by theory. This cubic hard-phase can be incorporated into amorphous boron-carbon matrices to yield superhard materials with tunable hardness values.http://www.mdpi.com/1996-1944/11/8/1279boron-carbon compoundsuperhard materialsab initio calculationschemical vapor deposition
institution	Open Data Bank
collection	Open Access Journals
building	Directory of Open Access Journals
language	English
format	Article
author	Paul A. Baker Shane A. Catledge Sumner B. Harris Kathryn J. Ham Wei-Chih Chen Cheng-Chien Chen Yogesh K. Vohra
spellingShingle	Paul A. Baker Shane A. Catledge Sumner B. Harris Kathryn J. Ham Wei-Chih Chen Cheng-Chien Chen Yogesh K. Vohra Computational Predictions and Microwave Plasma Synthesis of Superhard Boron-Carbon Materials Materials boron-carbon compound superhard materials ab initio calculations chemical vapor deposition
author_facet	Paul A. Baker Shane A. Catledge Sumner B. Harris Kathryn J. Ham Wei-Chih Chen Cheng-Chien Chen Yogesh K. Vohra
author_sort	Paul A. Baker
title	Computational Predictions and Microwave Plasma Synthesis of Superhard Boron-Carbon Materials
title_short	Computational Predictions and Microwave Plasma Synthesis of Superhard Boron-Carbon Materials
title_full	Computational Predictions and Microwave Plasma Synthesis of Superhard Boron-Carbon Materials
title_fullStr	Computational Predictions and Microwave Plasma Synthesis of Superhard Boron-Carbon Materials
title_full_unstemmed	Computational Predictions and Microwave Plasma Synthesis of Superhard Boron-Carbon Materials
title_sort	computational predictions and microwave plasma synthesis of superhard boron-carbon materials
publisher	MDPI AG
series	Materials
issn	1996-1944
publishDate	2018-07-01
description	Superhard boron-carbon materials are of prime interest due to their non-oxidizing properties at high temperatures compared to diamond-based materials and their non-reactivity with ferrous metals under extreme conditions. In this work, evolutionary algorithms combined with density functional theory have been utilized to predict stable structures and properties for the boron-carbon system, including the elusive superhard BC5 compound. We report on the microwave plasma chemical vapor deposition on a silicon substrate of a series of composite materials containing amorphous boron-doped graphitic carbon, boron-doped diamond, and a cubic hard-phase with a boron-content as high as 7.7 at%. The nanoindentation hardness of these composite materials can be tailored from 8 GPa to as high as 62 GPa depending on the growth conditions. These materials have been characterized by electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, X-ray diffraction, and nanoindentation hardness, and the experimental results are compared with theoretical predictions. Our studies show that a significant amount of boron up to 7.7 at% can be accommodated in the cubic phase of diamond and its phonon modes and mechanical properties can be accurately modeled by theory. This cubic hard-phase can be incorporated into amorphous boron-carbon matrices to yield superhard materials with tunable hardness values.
topic	boron-carbon compound superhard materials ab initio calculations chemical vapor deposition
url	http://www.mdpi.com/1996-1944/11/8/1279
_version_	1612680083559940096

Computational Predictions and Microwave Plasma Synthesis of Superhard Boron-Carbon Materials

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