Trapping, diffusion and release of helium in single-crystal TiC observed by thermal desorption spectrometry

Hoondert, W.H.B.; Thijsse, Barend J.; Veen, A. van; Beukel, A. van den

doi:10.1016/0257-8972(92)90261-8

Cited by 6 publications

(4 citation statements)

References 16 publications

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“…Another possibility under discussion is that the compound is maximally stable at stoichiometry, and that the large number of carbon vacancies is rather due to a kinetic effect. In the latter scenario, the energy barriers for migration of carbon in these systems are very large [7][8][9][10][11] and vacancies present during growth therefore effectively become frozen in, since the carbon atoms cannot move and fill the empty spaces in the structure. The following simple example illustrates the consequences of the large migration barriers: Based on experimental data, the interdiffusion coefficient D of C in TiC x as a function of carbon concentration and temperature can be expressed as D = [0.48 exp (9.2(1 − x))] exp (−39 500/T) cm 2 s −1 , where T is the absolute temperature [8].…”

Section: Introductionmentioning

confidence: 99%

Density functional study of carbon vacancies in titanium carbide

Råsander

Hugosson

Delin

2017

J. Phys.: Condens. Matter

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It is well established that TiC contains carbon vacancies not only in carbon-deficient environments but also in carbon-rich environments. We have performed density functional calculations of the vacancy formation energy in TiC for C- as well as Ti-rich conditions using several different approximations to the exchange-correlation functional, and also carefully considering the nature and thermodynamics of the carbon reference state, as well as the effect of varying growth conditions. We find that the formation of carbon vacancies is clearly favorable under Ti-rich conditions, whereas it is slightly energetically unfavorable under C-rich conditions. Furthermore, we find that the relaxations of the atoms close to the vacancy site are rather long-ranged, and that these relaxations contribute significantly to the stabilization of the vacancy. Since carbon vacancies in TiC are also experimentally observed in carbon-rich environments, we conclude that kinetics may play an important role. This conclusion is consistent with the experimentally observed high activation energies and sluggish diffusion of vacancies in TiC, effectively causing a freezing in of the vacancies.

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Section: Introductionmentioning

confidence: 99%

Density functional study of carbon vacancies in titanium carbide

Råsander

Hugosson

Delin

2017

J. Phys.: Condens. Matter

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“…Tsetseris et al 19 and Razumovskiy et al 20 have investigated the migration energy barriers for a number of diffusion processes in binary TiC in good agreement with experimentally obtained migration energy barriers. [21][22][23][24] It is well established, however, that C is the most mobile element in TiC.…”

Section: Introductionmentioning

confidence: 99%

A first principles study of the stability and mobility of defects in titanium carbide

Råsander,

Sanyal,

Jansson

et al. 2013

Preprint

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We have performed density functional calculations of the formation energies of substitutional transition metal (TM) defects, C vacancies, and C interstitial defects in TiC. In addition we have evaluated the migration energy barriers for C atoms in the presence of TM impurities. We find that the solubility of TM impurities taken from the 3d TM series is low and only Sc and V impurities can be dissolved into TiC at equilibrium. In addition, we find that the migration energy barriers of C in TiC are greatly affected by the presence of TM impurities: The migration barriers are generally lower in the presence of impurities compared to pure TiC and show a clear dependence on the atomic size of the TM impurities. We propose that the mobility of C in TiC will be the highest in the presence of TM impurities from the middle of the 3d TM series.

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“…The mechanical properties of thin coatings, such as coating cohesiveness and bonding to the substrate, are influenced by coating stresses, which are characteristic to the deposition conditions used. 3,4 Excess carbon often segregates to grain boundaries in the amorphous form. This facilitates grain boundary sliding and additional ductility, which helps in the prevention of fracture under severe loading conditions.…”

Section: Introductionmentioning

confidence: 99%

“…In practice, TiC always has a deficiency of carbon, containing a high concentration of structural vacancies in the carbon sublattice. The mechanical properties of thin coatings, such as coating cohesiveness and bonding to the substrate, are influenced by coating stresses, which are characteristic to the deposition conditions used 3,4. Excess carbon often segregates to grain boundaries in the amorphous form.…”

Section: Introductionmentioning

confidence: 99%

Tribological properties of nanostructured TiC coatings deposited on steel and silicon substrates using pulse laser deposition technique

Kumar

Krishnan

Kumar³

et al. 2011

Tribology - Materials, Surfaces & Interfaces

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Thin coatings of nanostructured titanium carbide (TiC) were deposited on silicon (Si) and stainless steel (AISI 304LN SS) substrates using pulse laser deposition technique. In these experiments, the deposition parameters were kept constant except deposition pressure. Change in the deposition partial pressure of CH 4 gas did not significantly influence the morphology and phase constituents of TiC coatings. In this regard, the tribological properties of these coatings were found to be almost similar. Coating thickness and surface roughness were found to alter with the type of substrate used. The tribological properties of these thin coatings were evaluated as a function of the different sliding counter bodies. The tribological properties were also studied on Si and SiO 2 to find out the role of substrate on friction and wear. The contact deformations as well as the morphologies of wear scars were found to influence the coefficient of friction.

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Trapping, diffusion and release of helium in single-crystal TiC observed by thermal desorption spectrometry

Cited by 6 publications

References 16 publications

Density functional study of carbon vacancies in titanium carbide

Density functional study of carbon vacancies in titanium carbide

A first principles study of the stability and mobility of defects in titanium carbide

Tribological properties of nanostructured TiC coatings deposited on steel and silicon substrates using pulse laser deposition technique

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