Compounds isoelectronic with diamond as a basis for the creation of new hard and super-hard materials

Zhogolev, D. A.; Bugaets, O.P.; Marushko, I. A.

doi:10.1007/bf00745976

Cited by 8 publications

(8 citation statements)

References 1 publication

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“…First, it is isoelectronic with diamond and C 3 N 4 , and has been suggested as a potential hard material. 15 Second, the composition is close to the carbonnitrogen ratio observed by e.g. Sjöstrom et al 10 for buckled turbostratic CN x microstructures formed at a high substrate temperature.…”

Section: Introductionmentioning

confidence: 65%

Electronic density of states,1score-level shifts, and core ionization energies of graphite, diamond,C3N
Snis
¹
,
Matar
²

1999
Phys. Rev. B
75
5
44
0
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The full-potential linearized augmented plane wave method has been employed to determine electronic density of states, 1s core level shifts, and total 1s core ionization energies for the isoelectronic compounds graphite, diamond, C 3 N 4 , and graphitic C 11 N 4 . The C 3 N 4 crystal structures studied are the graphitic, ␣, ␤, cubic, and pseudocubic configurations. All the C sp 3 bonded structures have band gaps 0.5-1.5 eV smaller than that of diamond. Only the C 3 N 4 composition of the C sp 2 phases has a band gap. The core level shifts and ionization energies are compared with x-ray photoelectron energies. The 1s energies of C atoms connected to zero, one, two, and three N in C 11 N 4 are close to experimental XPS shifts and peak positions. Nearly all the N 1s energies are within the experimental nitrogen XPS energy range. The C 1s ionization energies of the tetrahedral carbon C 3 N 4 phases are between 288.6-289.5 eV, which is 4.0-4.9 eV higher than the C 1s value of pure graphite. ␤-C 3 N 4 has the highest value. This compound has two N 1s ionization energies at approximately 400.0 and 400.6 eV. ͓S0163-1829͑99͒14239-5͔

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Section: Introductionmentioning

confidence: 65%

Electronic density of states,1score-level shifts, and core ionization energies of graphite, diamond,C3N
Snis
¹
,
Matar
²

1999
Phys. Rev. B
75
5
44
0
View full text Add to dashboard Cite

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“…39͒ and has been suggested as a possible hard material. 27 The configuration with layers in a stacking sequence AAA has been fully geometry optimized with the same ab initio pseudopotential plane-wave program. 34 Details on the geometry and on the electronic properties can be found in the above-cited papers.…”

Section: A the Graphitic And Pseudocubic C 3 Nmentioning

confidence: 99%

“…We have here restricted our investigation to a novel class of compounds electronically analogous to diamond for which the same four averaged number of valence electrons per atom is kept. [27][28][29] All the substances that satisfy this rule should possess similar properties to diamond, which is nowadays the hardest known material.…”

Section: Introductionmentioning

confidence: 99%

Density-functional theory investigation of hardness, stability, and electron-energy-loss spectra of carbon nitrides withC11N4stoichiometry

2002

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The characterization of carbon nitride films with stoichiometry C 3 N 4 is heavily restricted by the problem of getting pure crystalline samples with the right C/N ratio. However, thin films with lower nitrogen concentration ͑5-25 %͒ have been found relatively easier to deposit, for example, with reactive magnetron sputtering. It is also in this range of nitrogen content that the recently discovered ''graphiticlike → fullerenelike'' phase transition has been suggested to take place. Therefore, in order to add more information to the above experimental evidence, it is important to use theoretical methods to obtain further characterization of carbon nitride models with a high C/N ratio such as that of C 11 N 4 . It is relevant to propose a cross checking on the role played by the nitrogen concentration in determining the stability, hardness, and electronic properties of CN x compounds with different stoichiometries. For the sake of simplicity we have here compared the C 3 N 4 and C 11 N 4 systems, which are isoelectronic to each other. For this purpose two C 11 N 4 phases, namely, ␣ and ␤, are presented and investigated with density-functional-theory methods within the local density approximation. These phases contain less than ϳ30% of nitrogen than the well-known C 3 N 4 and are formally derived from the so-called pseudocubic C 3 N 4 . Cohesive properties, heats of formation, bulk and elastic moduli have been calculated and a full detailed analysis of the density-of-states and energy-loss-near-edge-structure spectra is presented. We propose that the lowering of the nitrogen concentration does not prevent the finding of new ultrahard materials and indeed brings a significant increase in the cohesive energy of carbon nitrides. However, the computed enthalpies of formation have shown values that are positive and generally larger than the analog carbon-deficient phases.

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“…Of particular interest is the synthesized ternary superhard material, BC 2 N, the second hardest known material with a Vickers hardness of 76 GPa 5 . Meanwhile, there are also several theoretical approaches 16 17 18 for designing and predicting new potential superhard materials to complement experimental works. A characteristic feature of the electronic structure of diamond, essential for its hardness, is the presence, in the valence level of each carbon atom, of four electrons capable of taking part in the formation of four strong tetrahedrally directed covalent bonds.…”

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confidence: 99%

Influences of carbon concentration on crystal structures and ideal strengths of B2CxO compounds in the B-C-O system

Yan

Zheng

Wei

2015

Sci Rep

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The search for novel superhard materials with special structures and improved thermal stability and hardness remains considerably experimental and theoretical challenges. Recent reports proposed that higher carbon content in ternary B2CxO compounds, which are isoelectronic with diamond, would lead to increased strength and hardness. This notion was derived from the calculated elastic parameters and empirical hardness formulas based on structural and electronic properties of the equilibrium structures. In present work, we introduce three potential ultra-incompressible and thermodynamically stable B2CxO (x ≥ 2) phases via a systematic particle swarm optimization algorithm structure searches. By evaluating the trends of the crystal configuration, electronic structure, and mechanical properties as a function of the C concentration, it is found that the high carbon concentration benefits the formation of the sp3 C-C covalent bonds and leads to the enhanced elastic moduli and ideal strengths in these B2CxO compounds. Studies of strain-stress behavior at large deformation, however, indicate that all these B2CxO compounds possess substantially lower ideal shear strengths than those of diamond and c-BN, suggesting that they may not be intrinsically superhard.

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Compounds isoelectronic with diamond as a basis for the creation of new hard and super-hard materials

Cited by 8 publications

References 1 publication

Electronic density of states,1score-level shifts, and core ionization energies of graphite, diamond,C3N
Snis
¹
,
Matar
²

1999
Phys. Rev. B
75
5
44
0
View full text Add to dashboard Cite

Electronic density of states,1score-level shifts, and core ionization energies of graphite, diamond,C3N
Snis
¹
,
Matar
²

1999
Phys. Rev. B
75
5
44
0
View full text Add to dashboard Cite

Density-functional theory investigation of hardness, stability, and electron-energy-loss spectra of carbon nitrides withC11N4stoichiometry

Influences of carbon concentration on crystal structures and ideal strengths of B2CxO compounds in the B-C-O system

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Compounds isoelectronic with diamond as a basis for the creation of new hard and super-hard materials

Cited by 8 publications

References 1 publication

Electronic density of states,1score-level shifts, and core ionization energies of graphite, diamond,C3NSnis1, Matar2 1999Phys. Rev. B755440View full textAdd to dashboardCite

Electronic density of states,1score-level shifts, and core ionization energies of graphite, diamond,C3NSnis1, Matar2 1999Phys. Rev. B755440View full textAdd to dashboardCite

Density-functional theory investigation of hardness, stability, and electron-energy-loss spectra of carbon nitrides withC11N4stoichiometry

Influences of carbon concentration on crystal structures and ideal strengths of B2CxO compounds in the B-C-O system

Contact Info

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Resources

About

Electronic density of states,1score-level shifts, and core ionization energies of graphite, diamond,C3N
Snis
¹
,
Matar
²

1999
Phys. Rev. B
75
5
44
0
View full text Add to dashboard Cite

Electronic density of states,1score-level shifts, and core ionization energies of graphite, diamond,C3N
Snis
¹
,
Matar
²

1999
Phys. Rev. B
75
5
44
0
View full text Add to dashboard Cite