Influence of carbon content on the crystallographic structure of boron carbide films

Boron carbide thin films were synthesised by laser-assisted chemical vapour deposition (LCVD), using a CO2 laser beam and boron trichloride and methan e as precursors. Boron and carbon contents were measured by electron probe microanalysis (EPMA). Microstructural analysis was carried out by Raman mic rospectroscopy and glancing-incidence X-ray diffraction (GIXRD) was used to study the crystallographic structure and to determine the lattice paramete rs of the polycrystalline films. The rhombohedral-hexagonal boron carbide c rystal lattice constants were plotted as a function of the carbon content, and the non-linear behaviour observed was interpreted on the basis of the c omplex structure of boron carbide. (C) 2000 Elsevier Science S.A. All right s reserved.