Crystal growth at high pressure and the problem of characterization of the interstitial phases in the B–C–O system

Gladkaya, I. S.; Dyuzheva, T. I.; Екимов, Е. А.; Николаев, Н. А.; Bendeliani, N. A.

doi:10.1016/s0925-8388(01)01612-7

Cited by 10 publications

(12 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Substitution of C for O expands the a and b lattice parameters by 0.13%, whereas contracting the c lattice parameter by 0.04%. The increase in the a parameter and decrease in the c parameter are in agreement with the experiments . The C O atom is threefold coordinated to three B e with B e –C O bond length of 1.52 Å and one O atom at a distance of 3.07 Å.…”

Section: Resultssupporting

confidence: 87%

See 1 more Smart Citation

Carbon Doping in Boron Suboxide: Structure, Energetics, and Elastic Properties

2015

View full text Add to dashboard Cite

The structural, electronic, and elastic properties of pristine and carbon‐doped boron suboxide (B6O) are calculated using density functional theory. The results indicate that it is energetically preferable for a single carbon atom to substitute into an oxygen site rather than a boron site. The lattice parameters and cell volume increase to relieve the residual stress created by the carbon substitution. The interstitial position is not favorable for a single atom substitution. However, if two carbon atoms substitute for two neighboring oxygen atoms, then it becomes energetically favorable to dope an interstitial oxygen, boron, or carbon atom along the C–C chain. If the interstitial dopant is either boron or carbon, a local B4C‐like structure with either a C–B–C or C–C–C chain is created within the boron suboxide unit cell. The resulting structure shows improvements in the bulk modulus at the expense of the shear and Young's moduli. The moduli further improve if an additional carbon is substituted within a polar or equatorial site of the neighboring B12 icosahedron. Based on these calculations, we conclude that carbon doping can either harden or soften B6O depending on the manner in which the substitutions are populated. Furthermore, as B6O samples are often oxygen deficient, C doping can occupy such sites and improve the elastic properties.

show abstract

Section: Resultssupporting

confidence: 87%

“…Also at the ambient conditions, the oxygen concentration in B 6 O is slightly lower than the ideal stoichiometry (B 6 O) . This means that some of the O sites are unoccupied in B 6 O lattice.…”

Section: Resultsmentioning

confidence: 95%

Carbon Doping in Boron Suboxide: Structure, Energetics, and Elastic Properties

2015

View full text Add to dashboard Cite

show abstract

“…Typically, these synthesis routes result in powder samples and can be performed near or at ambient pressure as well as at higher pressures. Samples prepared near ambient pressure are generally oxygen deficient, B 6 O x ( x <0.9), with rather poor crystallinity, whereas well‐crystallized icosahedral, multiply‐twinned stoichiometric B 6 O single crystals 40 μm in diameter were obtained at high pressures (4.0–5.5 GPa) and high temperatures (1700°–1800°C) 4,7,16–18 …”

Section: Introductionmentioning

confidence: 99%

B₆O: A Correlation Between Mechanical Properties and Microstructure Evolution upon Al₂O₃ Addition During Hot Pressing

Kleebe¹,

Lauterbach²,

Shabalala

et al. 2008

Journal of the American Ceramic Society

View full text Add to dashboard Cite

B6O powders were hot pressed with and without Al2O3 as a sintering additive at temperatures up to 1900°C and a pressure of 50 MPa. The microstructure of a doped and undoped sample was studied by transmission electron microscopy techniques. This paper aims at studying the correlation between micro/nanostructure evolution and the resulting mechanical properties; i.e., hardness and fracture toughness. The addition of alumina yields the formation of a secondary aluminum borate phase in addition to promoting grain growth strongly. While the addition of Al2O3 slightly decreased the hardness of the B6O polycrystals, the corresponding fracture toughness was strongly improved, as compared with the undoped material.

show abstract

“…High pressure applied during the synthesis of B 6 O can significantly increase the crystallinity, oxygen stoichiometry, and crystal size of the products. 5,11,20 Mixtures of boron and boron oxide (B 2 O 3 ) powders were usually used as starting materials in the reported methods for B 6 O synthesis. When the temperature-pressure conditions reach a critical point, nucleation of B 6 O was initiated randomly throughout the sample.…”

mentioning

confidence: 99%

“…The B 6 O crystals obtained in this way were smaller than 40 m in size, even at high pressure. 11,20,21 Recently, we tested a different sample assembly for B 6 O crystal growth at high pressure and high temperature, in which a lump of crystalline boron was surrounded by boron oxide powder in a hexagonal boron nitride ͑hBN͒ capsule. 21 We found that the boron first dissolved into the B 2 O 3 flux to form a B 6 6 O crystals over 100 m in size have been synthesized by the above method.…”

mentioning

confidence: 99%

Boron suboxide: As hard as cubic boron nitride

Zhao

Daemen

et al. 2002

Applied Physics Letters

271

163

View full text Add to dashboard Cite

The Vickers hardness of boron suboxide single crystals was measured using a diamond indentation method. Under a loading force of 0.98 N, our test gave an average Vickers hardness of 45 GPa. The average fracture toughness was measured as 4.5 MPa m1/2. We also measured the hardness of the cubic boron nitride and sapphire single crystals for comparison. The average measured hardness for boron suboxide was found to be very close to that of cubic boron nitride under the same loading force. Our results suggest that the boron suboxide could be a new superhard material for industrial applications, surpassed in hardness only by diamond and cubic boron nitride.

show abstract

Crystal growth at high pressure and the problem of characterization of the interstitial phases in the B–C–O system

Cited by 10 publications

References 8 publications

Carbon Doping in Boron Suboxide: Structure, Energetics, and Elastic Properties

Carbon Doping in Boron Suboxide: Structure, Energetics, and Elastic Properties

B₆O: A Correlation Between Mechanical Properties and Microstructure Evolution upon Al₂O₃ Addition During Hot Pressing

Boron suboxide: As hard as cubic boron nitride

Contact Info

Product

Resources

About

Crystal growth at high pressure and the problem of characterization of the interstitial phases in the B–C–O system

Cited by 10 publications

References 8 publications

Carbon Doping in Boron Suboxide: Structure, Energetics, and Elastic Properties

Carbon Doping in Boron Suboxide: Structure, Energetics, and Elastic Properties

B6O: A Correlation Between Mechanical Properties and Microstructure Evolution upon Al2O3 Addition During Hot Pressing

Boron suboxide: As hard as cubic boron nitride

Contact Info

Product

Resources

About

B₆O: A Correlation Between Mechanical Properties and Microstructure Evolution upon Al₂O₃ Addition During Hot Pressing