Bonding study of TiC and TiN. I. High-precision x-ray-diffraction determination of the valence-electron density distribution, Debye-Waller temperature factors, and atomic static displacements in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">TiC</mml:mi></mml:mrow><mml:mrow><mml:mn>0.94</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow

“…The lattice relaxation around vacancies in TiC consists in a shortening of the strengthened Ti-C bonds [14,16,17], which stabilizes the vacancies even further, especially at small concentrations.…”

mentioning

confidence: 99%

Ab InitioStudy of Phase Equilibria inTiCx

et al. 2001

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“…The stable bulk crystal structure of TiC is the rocksalt structure, with lattice constant of 4.332Å from our structure optimization [3] (experiment: 4.330Å [6]) and a calculated cohesive energy of 14.75 eV. The bonding [3,8] is characterized by spatially directed Ti-C bonds that secure strength, structure, and hardness [7].…”

Section: Brief Account Of Tic Resultsmentioning

confidence: 99%

Trends in atomic adsorption on titanium carbide and nitride

2006

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on the polar TiC(111) and TiN(111) yield similar adsorption trends for the two surfaces: (i) pyramid-like adsorption-energy trends along the adatom periods; (ii) strongest adsorption for O, C, N, S, and F; (iii) large adsorption variety; (iv) record-high adsorption energy for O (8.4 -8.8 eV). However, a stronger adsorption on TiN is found for elements on the left of the periodic table and on TiC for elements on the right. The results support that a concerted-coupling model, proposed for chemisorption on TiC, applies also to TiN.

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“…14 Usually, the formation of metal-carbon bonds modifies the electronic properties of the metal, producing a decrease in its density of states near the Fermi level and a metal→ carbon charge transfer. 8,14,15,18,25 In these materials, the chemical bonding exhibits a mixed character. 25,[30][31][32][33] For example, the valence bands of VC show a strong hybridization of the V͑3d͒ and C͑2p͒ states as expected for a covalent compound, 25,31 but there is, nevertheless, a rather large degree of ionicity in the V -C bonds with a positive Mulliken charge of ϳ1e on the V atoms.…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3][4][5][6][7][8] Traditionally, the oxides have been the compounds with the largest number of technological applications, 1,3,5,[9][10][11][12] but in the last two decades carbides and nitrides are receiving a lot of attention. [6][7][8][13][14][15][16][17][18][19][20][21][22][23][24][25] In broad terms, early transition metal carbides display a unique combination of the physical properties characteristic of noble metals and ceramics. 6,7,25 Many early transition metal carbides are good electrical and thermal conductors while possessing ultrahardness and very high melting points.…”

Section: Introductionmentioning

confidence: 99%

Interaction of oxygen with ZrC(001) and VC(001): Photoemission and first-principles studies

et al. 2005

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High-resolution photoemission and first-principles density-functional calculations were used to study the interaction of oxygen with ZrC͑001͒ and VC͑001͒ surfaces. Atomic oxygen is present on the carbide substrates after small doses of O 2 at room temperature. At 500 K, the oxidation of the surfaces is fast and clear features for ZrO x or VO x are seen in the O͑1s͒, Zr͑3d͒, and V͑2p 3/2 ͒ core levels spectra, with an increase in the metal/carbon ratio of the samples. A big positive shift ͑1.3-1.6 eV͒ was detected for the C 1s core level in O / ZrC͑001͒, indicating the existence of strong O ↔ C or C↔ C interactions. A phenomenon corroborated by the results of first-principles calculations, which show a CZrZr hollow as the most stable site for the adsorption of O. Furthermore, the calculations also show that a C ↔ O exchange is exothermic on ZrC͑001͒, and the displaced C atoms bond to CZrZr sites. In the O / ZrC͑001͒ interface, the surface C atoms play a major role in determining the behavior of the system. In contrast, the adsorption of oxygen induces very minor changes in the C͑1s͒ spectrum of VC͑001͒. The O ↔ V interactions are stronger than the O ↔ Zr interactions, and O ↔ C interactions do not play a dominant role in the O / VC͑001͒ interface. In this system, C ↔ O exchange is endothermic. VC͑001͒ has a larger density of metal d states near the Fermi level than ZrC͑001͒, but the rate of oxidation of VC͑001͒ is slower. Therefore the O / ZrC͑001͒ and O / VC͑001͒ systems illustrate two different types of pathways for the oxidation of carbide surfaces.

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Bonding study of TiC and TiN. I. High-precision x-ray-diffraction determination of the valence-electron density distribution, Debye-Waller temperature factors, and atomic static displacements inTiC0.94and

Cited by 143 publications

References 29 publications

Ab InitioStudy of Phase Equilibria inTiCx

Ab InitioStudy of Phase Equilibria inTiCx

Trends in atomic adsorption on titanium carbide and nitride

Interaction of oxygen with ZrC(001) and VC(001): Photoemission and first-principles studies

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