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Title: Elastic properties, sp³ fraction, and Raman scattering in low and high pressure synthesized diamond-like boron rich carbides

Dense BC{sub x} phases with high boron concentration are predicted to be metastable, superhard, and conductors or superconductors depending on boron concentration. However, up to this point, diamond-like boron rich carbides BC{sub x} (dl-BC{sub x}) phases have been thought obtainable only through high pressure and high temperature treatment, necessitating small specimen volume. Here, we use electron energy loss spectroscopy combined with transmission electron microscopy, Raman spectroscopy, surface Brillouin scattering, laser ultrasonics (LU) technique, and analysis of elastic properties to demonstrate that low pressure synthesis (chemical vapor deposition) of BC{sub x} phases may also lead to the creation of diamond-like boron rich carbides. The elastic properties of the dl-BC{sub x} phases depend on the carbon sp²versus sp³ content, which decreases with increasing boron concentration, while the boron bonds determine the shape of the Raman spectra of the dl-BC{sub x} after high pressure-high temperature treatment. Using the estimation of the density value based on the sp³ fraction, the shear modulus μ of dl-BC₄, containing 10% carbon atoms with sp³ bonds, and dl-B₃C₂, containing 38% carbon atoms with sp³ bonds, were found to be μ = 19.3 GPa and μ = 170 GPa, respectively. The presented experimental data also imply that boron atomsmore » lead to a creation of sp³ bonds during the deposition processes.« less
Authors:
; ; ; ;  [1] ;  [2] ;  [3] ;  [4]
  1. Hawaii Institute of Geophysics and Planetology, University of Hawaii, Honolulu, Hawaii 96822 (United States)
  2. Science and Technology on Thermostructure Composite Materials Laboratory, Northwestern Polytechnical University, Xi'an Shanxi (China)
  3. National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)
  4. Laboratory of High Pressure Physics, Southwest Jiaotong University, Chengdu, Sichuan (China)
Publication Date:
OSTI Identifier:
22305749
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 13; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ATOMS; BORON COMPOUNDS; BRILLOUIN EFFECT; CARBIDES; CHEMICAL VAPOR DEPOSITION; CONCENTRATION RATIO; DENSITY; ECOLOGICAL CONCENTRATION; ELASTICITY; ENERGY-LOSS SPECTROSCOPY; LASER RADIATION; PRESSURE RANGE GIGA PA; RAMAN EFFECT; RAMAN SPECTRA; RAMAN SPECTROSCOPY; SURFACES; SYNTHESIS; TRANSMISSION ELECTRON MICROSCOPY; ULTRASONIC WAVES