October 18, 2002
Boron carbide thin films were synthesised by laser-assisted chemical vapour deposition (LCVD), using a CO2 laser beam and boron trichloride and methane as precursors. Boron and carbon contents were measured by electron probe microanalysis (EPMA). Microstructural analysis was carried out by Raman microspectroscopy and glancing incidence X-ray diffraction (GIXRD) was used to study the crystallographic structure and to determine the lattice parameters of the polycrystalline films. The rhombohedral-hexagonal boron carbide crystal lattice constants were plotted as a function of the carbon content, and the non-linear observed behaviour is interpreted on the basis of the complex structure of boron carbide. Keywords: Boron carbide; Laser CVD; crystallographic structure; micro-Raman spectroscopy.
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October 18, 2002
This paper focuses on the synthesis of rhombohedral B4C (r-B4C) coatings by CO2 laser-assisted chemical vapour deposition (LCVD), using a dynamic reactive atmosphere of BCl3, H2 and CH4 or C2H4. The influence of the carbon precursor on the deposition kinetics is discussed. The use of ethylene as carbon precursor presents several advantages over the use of methane, which is the conventional carbon precursor in CVD processes. These advantages are mainly related to its high abso...
October 18, 2002
Rhombohedral B4C coatings were synthesised on fused silica substrates by CO2 laser-assisted chemical vapour deposition (LCVD), using a dynamic reactive atmosphere of BCl3, C2H4 and H2. Films with carbon content from 15 to 22 at.% were grown at deposition rates as high as 0.12 micrometers per second. The kinetics of the reactive system used to deposit the B4C films and the influence of growth conditions on the structure and morphology of the deposits were investigated. Keywo...
October 19, 2017
Micron-thick boron films have been deposited by Pulsed Laser Deposition in vacuum on several substrates at room temperature. The use of high energy pulses (>700 mJ) results in the deposition of smooth coatings with low oxygen uptake even at base pressures of 10$^{-4}$ - 10$^{-3}$ Pa. A detailed structural analysis, by X-Ray Diffraction and Raman, allowed to assess the amorphous nature of the deposited films as well as to determine the base pressure that prevents boron oxide f...
August 24, 2017
Boron carbide thin films of different thicknesses deposited by ion beam sputtering were studied. The deposited films were characterized by grazing incidence hard x-ray reflectivity (GIXR), resonant soft x-ray reflectivity (RSXR), x-ray photo electron spectroscopy (XPS), resonant Rutherford backscattering spectrometry (RRBS), and time of flight secondary ion mass spectrometry (TOF-SIMS). An in-depth profile of the chemical elements constitute the films is reconstructed based o...
May 5, 2021
Boron carbide, a lightweight, high temperature material, has various applications as a structural material and as a neutron absorber. The large solubility range of carbon in boron, between $\approx$ 9% and 20%, stems from the thermodynamical stability of three icosahedral phases at low temperature, with respective carbon atomic concentrations: 8.7% (B$_{10.5}$C, named OPO$_1$), 13.0 \% (B$_{6.7}$C, named OPO$_2$), whose theoretical Raman spectra are still unknown, and 20% (B$...
September 13, 1999
The atomic structure of icosahedral B$_4$C boron carbide is determined by comparing existing infra-red absorption and Raman diffusion measurements with the predictions of accurate {\it ab initio} lattice-dynamical calculations performed for different structural models. This allows us to unambiguously determine the location of the carbon atom within the boron icosahedron, a task presently beyond X-ray and neutron diffraction ability. By examining the inter- and intra-icosahedr...
August 9, 2021
We report a combined experimental and theoretical study of boron carbide under stress/deformation. A special rotating anvil press, the rotating tomography Paris Edinburgh cell (RotoPEC), has been used to apply torsional deformation to boron carbide under a pressure of 5~GPa at ambient temperature. Subsequent damages and point defects have been analysed at ambient pressure by energy dispersive X-ray microdiffraction at the synchrotron and by Raman spectroscopy, combined with c...
August 25, 2019
The deposition of boron-doped amorphous carbon thin films on SiO2 substrate was achieved via a focused ion beam-assisted chemical vapor deposition of triphenyl borane (C18H15B) and triphenyl borate (C18H15BO3). The existence of boron in the deposited film from triphenyl borane, with a precursor temperature of 90 {\deg}C, was confirmed by a core level X-ray photoelectron spectroscopy analysis. The film exhibited a semiconducting behavior with a band gap of 285 meV. Although th...
January 31, 2013
Boron-doped single crystal diamond films were grown homoepitaxially on synthetic (100) Type Ib diamond substrates using microwave plasma assisted chemical vapor deposition. A modification in surface morphology of the film with increasing boron concentration in the plasma has been observed using atomic force microscopy. Use of nitrogen during boron doping has been found to improve the surface morphology and the growth rate of films but it lowers the electrical conductivity of ...
October 29, 2012
The boron-doped single crystal diamond films were grown homoepitaxially on synthetic (100) oriented Type Ib diamond substrates using a Microwave Plasma Chemical Vapor Deposition (MPCVD) technique. Raman spectrum showed a few additional bands at the lower wavenumber regions along with the zone center optical phonon mode for diamond. The change in the peak profile of the zone center optical phonon mode and its downshift were observed with the increasing boron content in the fil...