Some properties of single-crystal boron carbide

Confined Raman Scattering – Easy Access to the Surface Phonons of Specific Crystalline Solids

“…The surface phonon near 200 cm -1 (Figure 11c) consists essentially of three components, whose frequencies, intensities www.zaac.wiley-vch.de ARTICLE and peak half-widths are largely unaffected by the shares of boron isotopes in the crystal ( Figure 13). This supports their attribution to Raman-inactive acoustic modes of the La ion in agreement with the phonon dispersion curves [17,29] , showing threefold splitting at the Γ point.…”

“…According to Monnier and Delley, [25] the structure allows large, uncorrelated displacements of the La ions from their equilibrium positions, reflected in the weak dispersion of the acoustic branches near the Γ point. According to the dispersion curves [17,25] both modes are threefold split. The surface phonon near 200 cm -1 (Figure 11c) consists essentially of three components, whose frequencies, intensities www.zaac.wiley-vch.de ARTICLE and peak half-widths are largely unaffected by the shares of boron isotopes in the crystal ( Figure 13).…”

Electronic structures and mechanical properties of boron and boron-rich crystals (Part I)

“…The composition varies in some range, typically from B 12 C 3 to B 13 C 2 , but more C-poor compounds exist [42]. It is believed that the most C-rich compound obtained so far is close to the composition B 12 C 3 but is slightly less than that, which is sometime referred to as awkward name B 4.3 C [43,44]. The simplest polymorph is α-rhombohedral boron, which was isolated in 1959 [45].…”

Raman effect in icosahedral boron-rich solids

“…In this paper, we only show spectra of high-quality B 4.3 C single crystals [47,48]. Figure 6 shows the fundamental problem of the Raman spectroscopy of boron carbide: the spectra are qualitatively different when excited by different laser energies.…”

“…In the isostructural borides, the 2b positions and an additional interstitial void position 2a are completely or partly occupied by foreign, preferably metal atoms [101]. B 48 spectrum is shown in figure 19 [102]. Its unit cell contains four formula units.…”