FT-Raman spectra of isotope-enriched boron carbide

Werheit, H.; Rotter, H.; Meyer, Falko D.; Hillebrecht, Harald; Shalamberidze, Sulkhan; Abzianidze, T G; Esadze, G.G.

doi:10.1016/j.jssc.2003.04.004

Cited by 64 publications

(56 citation statements)

References 20 publications

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“…In boron carbide, the IR-active stretching vibration of the C-B-B and C-B-C chains corresponds to the frequency ∼1580 cm −1 (see [40] and references therein), and thus, the 321/270 cm −1 doublet fits to the bending mode quite well. The previous attribution to 'rotating C-B-C and C-B-B chains and accompanying wagging icosahedra' [52] was based on theoretical calculations by Shirai and Emura [120]. The calculated frequency of that librational mode (170 cm −1 ) was quite different from the experimental values.…”

Section: Boron Carbidementioning

confidence: 90%

Raman effect in icosahedral boron-rich solids

Werheit¹,

Филипов

Kuhlmann

et al. 2010

Science and Technology of Advanced Materials

133

116

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We present Raman spectra of numerous icosahedral boron-rich solids having the structure of α-rhombohedral, β-rhombohedral, α-tetragonal, β-tetragonal, YB 66 , orthorhombic or amorphous boron. The spectra were newly measured and, in some cases, compared with reported data and discussed. We emphasize the importance of a high signal-to-noise ratio in the Raman spectra for detecting weak effects evoked by the modification of compounds, accommodation of interstitial atoms and other structural defects. Vibrations of the icosahedra, occurring in all the spectra, are interpreted using the description of modes in α-rhombohedral boron by Beckel et al. The Raman spectrum of boron carbide is largely clarified. Relative intra-and inter-icosahedral bonding forces are estimated for the different structural groups and for vanadium-doped β-rhombohedral boron. The validity of Badger's rule is demonstrated for the force constants of inter-icosahedral B-B bonds, whereas the agreement is less satisfactory for the intra-icosahedral B-B bonds.

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Section: Boron Carbidementioning

confidence: 90%

Raman effect in icosahedral boron-rich solids

Werheit¹,

Филипов

Kuhlmann

et al. 2010

Science and Technology of Advanced Materials

133

116

View full text Add to dashboard Cite

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“…They assert that the ionicity of the bonds is sufficient for absorption in single phonone processes and analyzed the lattice vibrations in detail. [181][182][183][184] More importantly, their analysis of the spectra provides quantitative results of the proportions of the various structural units in boron carbide, depending on the composition. A sample of composition B 4.3 C 100 % B 11 C versus 0 % B 12 , for example, 81 % CBC versus 19 % CBB and 0 % B&B, whereas B 13 C 2 contains 58 % B 11 C versus 42 % B 12 besides 62 % CBC versus 19 % CBB and 19 % B&B.…”

Section: General Observationsmentioning

confidence: 99%

Boron: Elementary Challenge for Experimenters and Theoreticians

Albert¹,

Hillebrecht²

2009

Angew Chem Int Ed

580

436

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Many of the fundamental questions regarding the solid-state chemistry of boron are still unsolved, more than 200 years after its discovery. Recently, theoretical work on the existence and stability of known and new modifications of the element combined with high-pressure and high-temperature experiments have revealed new aspects. A lot has also happened over the last few years in the field of reactions between boron and main group elements. Binary compounds such as B(6)O, MgB(2), LiB(1-x), Na(3)B(20), and CaB(6) have caused much excitement, but the electron-precise, colorless boride carbides Li(2)B(12)C(2), LiB(13)C(2), and MgB(12)C(2) as well as the graphite analogue BeB(2)C(2) also deserve special attention. Physical properties such as hardness, superconductivity, neutron scattering length, and thermoelectricity have also made boron-rich compounds attractive to materials research and for applications. The greatest challenges to boron chemistry, however, are still the synthesis of monophasic products in macroscopic quantities and in the form of single crystals, the unequivocal identification and determination of crystal structures, and a thorough understanding of their electronic situation. Linked polyhedra are the dominating structural elements of the boron-rich compounds of the main group elements. In many cases, their structures can be derived from those that have been assigned to modifications of the element. Again, even these require a critical revision and discussion.

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“…B 13 C 2 zu erwarten ist. [24] Damit ist die starke Raman-Bande bei 1477 cm À1 im Spektrum von Li 2 B 12 C 2 eindeutig der C-C-Schwingung zuzuordnen. Ein Vergleich mit Literaturdaten für C 2 H 4 (1619 cm À1 ), C 2 Cl 4 (1571 cm À1 ), C 2 Br 4 (1547 cm À1 ) und C 2 I 4 (1465 cm À1 ) [25] bestätigt einerseits den Doppelbindungscharakter, anderer- und bei Al 3 BC 3 bei 1580 cm À1 .…”

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