The electronic structure, total energy, and vibrational properties of C2 B10 H12 (carborane) molecules and C2 B10 clusters formed when the hydrogen atoms are removed from carborane molecules are studied using density functional methods and a semiempirical model. Computed vibrational spectra for carborane molecules are shown to be in close agreement with previously published measured spectra taken on carborane solids. Semiconducting boron carbide films are prepared by removing hydrogen from the three polytypes of C2 B10 H12 deposited on various surfaces. Results from x-ray and Raman scattering measurements on these films are reported. Eleven vibrationally stable structures for C2 B10 clusters are described and their energies and highest occupied and lowest unoccupied molecular orbital gaps tabulated. Calculated Raman and infrared spectra are reported for the six lowest-energy clusters. Good agreement with the experimental Raman spectra is achieved from theoretical spectra computed using a Boltzmann distribution of the six lowest-energy free clusters. The agreement is further improved if the computed frequencies are scaled by a factor of 0.94, a descrepancy which could easily arise from comparing results of two different systems: zero-temperature free clusters and room-temperature films. Calculated energies for removal of hydrogen pairs from carborane molecules are reported.
|Original language||English (US)|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - Feb 27 2006|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics