The properties and structure of the boron carbide phase

Bouchacourt, M.; Thévenot, F.

doi:10.1016/0022-5088(81)90223-x

Cited by 113 publications

(32 citation statements)

References 6 publications

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“…It is known that boron carbide has a wide non-stoichiometric range (9-20 at%C), 8) and the lattice parameters depend on the composition. 9,10) The lattice parameters of boron carbide in the B 4 C-SiC composites were in agreement with those of stoichiometric B 4 C (i.e., a = 0.561 nm and c = 1.209 nm in hexagonal expression).…”

Section: Methodssupporting

confidence: 67%

Characterization of Directionally Solidified B<SUB>4</SUB>C-SiC Composites Prepared by a Floating Zone Method

2002

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Directionally solidified B 4 C-SiC composites were prepared by a Floating Zone method. The lamellar texture was observed at 53 mol%SiC. The c-axis of B 4 C phase was tilted 20 • to the growth direction. The (102) plane and [121] direction of the B 4 C phase were parallel to the (311) plane and [121] direction of the SiC phase, respectively. The thermal conductivity of the composite parallel to the growth direction (κ ) was about twice as great as that of monolithic B 4 C. The anisotropy of electrical conductivity and thermal conductivity were explained by a mixing law using the values of B 4 C and SiC. The mass gain due to oxidation was about 1/3 to 1/5 less than that of monolithic B 4 C at 1023 K. The surface perpendicular to the growth direction showed slightly better oxidation resistance than that parallel to the growth direction. The microhardness of the composite was almost the same as that of B 4 C.

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Section: Methodssupporting

confidence: 67%

Characterization of Directionally Solidified B<SUB>4</SUB>C-SiC Composites Prepared by a Floating Zone Method

2002

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“…It was shown that the absolute change in value of lattice parameter C was larger than that of the parameter a (18). The elongation of the boron carbide crystal lattice, particularly in the direction of the hexagonal C axis, after hightemperature interaction between B C and Al has been established by Lipp and Roder (19).…”

Section: Resultsmentioning

confidence: 93%

Structural and Mechanical Properties of Activated Sintered Boron Carbide-Based Materials

Radev

Zakhariev

1998

Journal of Solid State Chemistry

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“…This wide composition range significantly affects the physical and mechanical properties of boron carbide. 5,8,10,[12][13][14] Elemental boron also exhibits B12 icosahedra in several stable crystalline forms.…”

Section: Introductionmentioning

confidence: 99%

Structure and Properties of Boron-Very-Rich Boron Carbides: B₁₂ Icosahedra Linked through Bent CBB Chains

Yang

Goddard

2018

J. Phys. Chem. C

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The atomic structures of boron carbide in the regime below ~13.3 at.% C (known as boron-veryrich boron carbide, BvrBC) have not previously been reported due to the complexity of the structure and bonding. We report here the atomistic crystal structures for stoichiometry B 14 C, with only 6.7 at.% C, predicted using quantum mechanics (QM) at the PBE level. We find that B 14 C consists of one B 12 icosahedral cluster and one C-B-B chain per unit cell. The C-B-B chain can be linear or bent, leading to two different space groups for (B 12 )CBB. Our bonding analyses show that both structures satisfy the electron counting rule (Wade's rule). However, the bent CBB chain which has lower crystal symmetry leads to an energy substantially more stable (0.315 eV per molecular unit) than the linear CBB chain structure, which has high crystal symmetry. This is because the bent CBB chain structure requires only one three-center−two-electron (3c-2e) bond while linear CBB chain structure requires three 3c-2e bonds. We predicted the mechanical properties of both structures from QM simulations. We found that shearing the linear CBB chain structure transforms first to the bent CBB chain structure under both pure and biaxial shear deformations. As the shear proceeds the icosahedra deconstruct due to the interaction of the CBB chains with the icosahedra. This suggests that the bent CBB structure is responsible for the failure processes of B 14 C.

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The properties and structure of the boron carbide phase

Cited by 113 publications

References 6 publications

Characterization of Directionally Solidified B<SUB>4</SUB>C-SiC Composites Prepared by a Floating Zone Method

Characterization of Directionally Solidified B<SUB>4</SUB>C-SiC Composites Prepared by a Floating Zone Method

Structural and Mechanical Properties of Activated Sintered Boron Carbide-Based Materials

Structure and Properties of Boron-Very-Rich Boron Carbides: B₁₂ Icosahedra Linked through Bent CBB Chains

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The properties and structure of the boron carbide phase

Cited by 113 publications

References 6 publications

Characterization of Directionally Solidified B<SUB>4</SUB>C-SiC Composites Prepared by a Floating Zone Method

Characterization of Directionally Solidified B<SUB>4</SUB>C-SiC Composites Prepared by a Floating Zone Method

Structural and Mechanical Properties of Activated Sintered Boron Carbide-Based Materials

Structure and Properties of Boron-Very-Rich Boron Carbides: B12 Icosahedra Linked through Bent CBB Chains

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Structure and Properties of Boron-Very-Rich Boron Carbides: B₁₂ Icosahedra Linked through Bent CBB Chains