Boron carbide structure by Raman spectroscopy

Journal Article · Fri Sep 15 04:00:00 EDT 1989 · Physical Review (Section) B: Condensed Matter; (USA)

DOI:https://doi.org/10.1103/PhysRevB.40.5649· OSTI ID:5575430

Tallant, D R; Aselage, T L; Campbell, A N; Emin, D ^[1]

---

1. Sandia National Laboratories, Albuquerque, New Mexico 87185 (US)

We have obtained and analyzed Raman spectra of single-crystal, hot-pressed, and chemical-vapor-deposited boron carbide materials over their single-phase region (from {similar to}9 to {similar to}20 at. % carbon). These spectra provide insight into the substitutional disorder that characterizes these structurally ordered solids. In particular, although icosahedra and chain structures occupy regular lattice positions, there is local substitutional disorder resulting from the occupancy of certain sites within the icosahedra and chains by either boron or carbon atoms. Comparison of boron carbide Raman spectra with the Raman spectra of {alpha}-rhombohedral boron, boron phosphide, and boron arsenide has confirmed the following structural model derived from theoretical considerations and electrical and thermal transport data. The boron carbide composition with nearly 20 at. % carbon is composed of B{sub 11}C icosahedra linked by carbon-boron-carbon chains. As the carbon content is reduced toward approximately 13 at. %, carbon-boron-carbon chains are progressively replaced by carbon-boron-boron chains. Further reduction in the carbon content results in the replacement of B{sub 11}C icosahedra with B{sub 12} icosahedra.

• DOE Contract Number: AC04-76DP00789
• OSTI ID: 5575430
• Journal Information: Physical Review (Section) B: Condensed Matter; (USA), Journal Name: Physical Review (Section) B: Condensed Matter; (USA) Vol. 40:8; ISSN PRBMD; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
BORON CARBIDES
BORON COMPOUNDS
CARBIDES
CARBON COMPOUNDS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
CRYSTAL-PHASE TRANSFORMATIONS
CRYSTALS
MONOCRYSTALS
MORPHOLOGICAL CHANGES
PHASE TRANSFORMATIONS
QUANTITY RATIO
RAMAN SPECTRA
SPECTRA
ULTRASTRUCTURAL CHANGES