Vacancy induced changes in the electronic structure of titanium carbide—I. Band structure and density of states

Redinger, Josef; Eibler, R.; Herzig, Peter; Neckel, A.; Podloucky, R.; Wimmer, E.

doi:10.1016/0022-3697(85)90183-0

Cited by 88 publications

(20 citation statements)

References 28 publications

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“…In the present paper the results showed two properties of the Ti-Ti interactions in the vacancy neighbourhood similar to the APW band structure calculations [6,7]. We observed in agreement with [6, 71 the direct Ti-n-Ti bond via the vacancy and the strengthening of the Ti,-Ti, first neighbour interactions about the vacancy in TIC, and TIN,.…”

Section: Discussionsupporting

confidence: 93%

“…In OTi,C,, the total charge is slightly lower on titanium and slightly higher on C,, carbons than in CTi,CI8 (Table 4). This means a greater localization of the electrons which can be interpreted as the increase of the ionic character of the bonding going from stoichiometric to substoichiometric titanium carbide in agreement with the APW band structure calculations [7]. The charges at the surface carbon atoms C,, C,, C, are influenced by the existence of the surface of the cluster and we can hardly draw any conclusion from their values.…”

Section: Atomic Chargesmentioning

confidence: 60%

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Chemical Bonding and Lattice Relaxation in Substoichiometric Titanium Carbide and Nitride

Čapková

Skála

1992

Physica Status Solidi (b)

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The rearrangement of interatomic interactions and redistribution ofelectron densities in titanium carbide and nitride resulting from the existence of the nonmetal vacancy are studied by the CND0/2 method. The local lattice relaxation is taken into account and the differences and common features in the behaviour of the nonmetal vacancy in titanium carbide and nitride are discussed.Die Umordnung der interatomaren Wechselwirkungen und die Umverteilung der Elektronendichte im Titankarbid und -nitrid, die aus der Existenz der nichtmetallischen Leerstelle folgen, werden mit der Hilfe der CNDO/2-Methode untersucht. Die lokale Gitterrelaxation wird beriicksichtigt und die Unterschiede und gemeinsamen Eigenschaften der nichtmetallischen Leerstelle im Titankarbid und -nitrid werden diskutiert.

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Section: Discussionsupporting

confidence: 93%

Section: Atomic Chargesmentioning

confidence: 60%

Chemical Bonding and Lattice Relaxation in Substoichiometric Titanium Carbide and Nitride

Čapková

Skála

1992

Physica Status Solidi (b)

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“…[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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“…[21] for some symmetry directions in the first Brillouin zone. The band structure of TiC shown in Figure 11 is entirely equivalent to the band structure in [8].…”

Section: Apw Band Structure Calculationsmentioning

confidence: 99%

Electronic Structure of Stoichiometric and Non-Stoichiometric Titanium Carbides and Nitrides

Neckel

1990

The Physics and Chemistry of Carbides, Nitrides and Borides

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ABSTRACT. In the present article a brief overview is given on the electronic structure and the nature of the chemical bonds in stoichiometric and substoichiometric titanium carbides and nitrides crystallizing in the sodium chloride structure. On the basis of APW band structure calculations it is shown that metallic, ionic, and covalent bonding occurs in the stoichiometric compounds. Three main types of covalent bonds can be distinguished: X 2p -Ti 3d 0 bonds, X 2p -Ti 3d n bonds, and Ti 3d -Ti 3d 0 bonds (X = C,N). The influence of vacancies at the non-metal sublattice sites on the electronic structure of the substoichiometric cubic phases TiX x was studied by two different approaches: (i) APW band structure calculations, assuming a hypothetical model structure with an ordered arrangement of vacancies, corresponding to the composition TiXO.75' (ii) KKR-CPA calculations, assuming a random distribution of vacancies and non-metal atoms over the non-metal sublattice sites. Both calculations lead to additional peaks ("vacancy peaks") in the density of states, induced by the vacancies. The changes in the covalent bonds, compared with the stoichiometric compounds, are discussed on the basis of local partial densities of states and electron densities. I • INTRODUCTIONRefractory transition metal carbides and nitrides crystallizing in the sodium chloride structure continue to be of considerable practical and theoretical interest. This class of substances exhibits, on the one hand, high melting points and ultrahardness -properties typical of covalent compounds -and, on the other hand, metallic properties, such as good electrical and thermal conductivity. Furthermore, these substances crystallize in the sodium chloride structure, which is generally found with ionic compounds. This unusual combination of properties has attracted an early and continuing interest in the electronic structure and nature of the chemical bonds in these substances.The electronic structure of the refractory transition metal

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Vacancy induced changes in the electronic structure of titanium carbide—I. Band structure and density of states

Cited by 88 publications

References 28 publications

Chemical Bonding and Lattice Relaxation in Substoichiometric Titanium Carbide and Nitride

Chemical Bonding and Lattice Relaxation in Substoichiometric Titanium Carbide and Nitride

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

Electronic Structure of Stoichiometric and Non-Stoichiometric Titanium Carbides and Nitrides

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