Structure of B6O boron-suboxide by Rietveld refinement

Kobayashi, Masayoshi; Higashi, Iwami; Brodhag, Christian; Thévenot, F.

doi:10.1007/bf00367573

Cited by 85 publications

(51 citation statements)

References 8 publications

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“…Addition of O to -rh B to form B O results in a shorter two-center intericosahedral bond and longer intraicosahedral bonds than in -rh B (19,20). The B K edge of B O is similar to that of -rh B, except for the loss of the pre-edge feature, A, and enhancement in intensity of peak B compared to the B K edge from -rh B.…”

Section: Energy-loss Near-edge Structurementioning

confidence: 97%

High-Pressure, High-Temperature Syntheses in the B–C–N–O System

Garvie

Hubert

Petuskey

et al. 1997

Journal of Solid State Chemistry

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Section: Energy-loss Near-edge Structurementioning

confidence: 97%

High-Pressure, High-Temperature Syntheses in the B–C–N–O System

Garvie

Hubert

Petuskey

et al. 1997

Journal of Solid State Chemistry

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“…17,18) On the other hand, boron suboxide (B 6 O) consists of B 12 icosahedrons and O-O two-atom chain [19][20][21] as shown in Fig. 1(b).…”

Section: Introductionmentioning

confidence: 99%

Thermoelectric Properties of Hot-pressed Boron Suboxide (B<SUB>6</SUB>O)

et al. 2002

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Boron suboxide (B 6 O) sintered bodies were prepared by a solid state reaction and a hot pressing method. The thermoelectric properties of B 6 O were compared with those of B 4 C. The electrical conductivity was smaller than that of B 4 C, and the Seebeck coefficient was twice as large as that of B 4 C indicating p-type conduction. The hopping conduction of electronic charge carriers was suggested from the temperature dependencies of the electrical conductivity and mobility. The thermal conductivity was greater than that of B 4 C. The thermoelectric dimensionless figure-of-merit increased with increasing temperature, and was 0.62 × 10 −3 at 1000 K. This value was almost in agreement with that of B 4 C.

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“…Boron suboxide, often denoted by B 6 O, is also a material of choice for a superhard material, as it is suspected to be the hardest Introduction material after diamond and cBN [67]. Refined by the Rietveld method applied on x-ray powder diffraction data [69,70], the crystal structure of boron suboxide can be derived from α-boron (R3m), as already shown in Fig. 1.1(d).…”

Section: Boron Suboxidementioning

confidence: 99%

First-principles study of configurational disorder in icosahedral boron-rich solids

Ektarawong¹

2015

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This thesis is a theoretical study of configurationally disordered icosahedral boronrich solids, in particular boron carbides, using density functional theory and alloy theory. The goal is to resolve discrepancies, regarding the properties of boron carbides, between experiments and previous theoretical calculations which have been a controversial issue in the field of icosahedral boron-rich solids. For instance, B 13 C 2 is observed experimentally to be a semiconductor, meanwhile electronic band structure calculations reveal a metallic character of B 13 C 2 due to its electron deficiency. In B 4 C, on the other hand, the experimentally observed band gap is unexpectedly smaller, not the usual larger, than that of standard DFT calculations. Another example is given by the existence of a small structural distortion in B 4 C, as predicted in theoretical calculations, which reduces the crystal symmetry from the experimentally observed rhombohedral (R3m) to the based-centered monoclinic (Cm). Since boron carbide is stable as a single-phase over a broad composition range (∼8-20 at.% C), substitution of boron and carbon atoms for one another is conceivable. For this reason, the discrepancies have been speculated in the literature, without a proof, to originate from configurational disorder induced by substitutional defects. However, owing to its complex atomic structure, represented by 12-atom icosahedra and 3-atom intericosahedral chains, a practical alloy theory method for direct calculations of the properties of the relevant configurations of disordered boron carbides, as well as for a thermodynamic assessment of their stability has been missing.In this thesis, a new approach, the superatom-special quasirandom structure (SA-SQS), has been developed. The approach allows one to model configurational disorder in boron carbide, induced by high concentrations of low-energy B/C substitutional defects. B 13 C 2 and B 4 C are the two stoichiometries, mainly considered in this study, as they are of particular importance and have been in focus in the literature. The results demonstrate that, from thermodynamic considerations, both B 13 C 2 and B 4 C configurationally disorder at high temperature. In the case of B 13 C 2 , the configurational disorder splits off some valence states into the band gap that in turn compensates the electron deficiency in ordered B 13 C 2 , thus resulting in a semiconducting character. As for B 4 C, the configurational disorder eliminates the monoclinic distortion, thus resulting in the restoration of the higher rhombohedral symmetry. Configurational disorder can also account for an exceliii iv lent agreement on elastic moduli of boron carbide between theory and experiment. Thus, several of the previous discrepancies between theory and experiments are resolved.Inspired by attempts to enhance the mechanical properties of boron suboxide by fabricating boron suboxide-boron carbide composites, as recently suggested in the literature, the SA-SQS approach is used for modeling mixtures of boron sub...

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Structure of B6O boron-suboxide by Rietveld refinement

Cited by 85 publications

References 8 publications

High-Pressure, High-Temperature Syntheses in the B–C–N–O System

High-Pressure, High-Temperature Syntheses in the B–C–N–O System

Thermoelectric Properties of Hot-pressed Boron Suboxide (B<SUB>6</SUB>O)

First-principles study of configurational disorder in icosahedral boron-rich solids

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