Some Features of the Nb-N and Nb-N-O Systems.

Schönberg, Nils; Overend, W. G.; Munthe-Kaas, A.; Sørensen, Nils Andreas

doi:10.3891/acta.chem.scand.08-0208

Cited by 98 publications

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“…TiC and TiN crystals belong to the same space group (FM-3 M, Cubic system), and in this study the experimental structures determined by Elliot et al [12] and Schoenberg [13] were chosen as the initial configurations respectively. The structural optimization and elastic constants of TiC and TiN crystals were calculated using the CASTEP plane-wave code [14] in the scheme of local density approximation (LDA-CA-PZ) [15] and generalized gradient approximation (GGA-PBE) [16].…”

Section: Calculation Detailsmentioning

confidence: 99%

First-principles calculations of mechanical properties of TiC and TiN

Yang

Lü

et al. 2009

Journal of Alloys and Compounds

248

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Section: Calculation Detailsmentioning

confidence: 99%

First-principles calculations of mechanical properties of TiC and TiN

Yang

Lü

et al. 2009

Journal of Alloys and Compounds

248

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Section: Introductionmentioning

confidence: 99%

“…[1] Another modification of tantalum mononitride, the δ-phase with a face-centered cubic B1 NaCl-type structure, was observed by Gerstenberg and Calbick [16] in thin films; it was also recently synthesized from the ε-phase by shock compression. [7] The lattice parameter (a ϭ 4.337 Å ) for this [1] TaN 0.04 3.315 [2] β-phase α-phase with a cubic 3 ϫ 3 ϫ 3 superstructure TaN 0.05 10.11 (3ϫ 3.369) [1] γ-phase (β-Ta 2 N) hexagonal close-packing of the tantalum atoms TaN 0.41 3.041 4.907 [1] TaN 0.5 3.042 4.905 [2] TaN 0.5 4.928 [3] an anti-Li 2 ZrF 6 -type superstructure with aЈ ϭ Ί3a 5.283 (Ί3 ϫ 3.050) TaN 0. 43 4.919 [4] 5 [3] hexagonal, distorted B35 CoSn-type TaN 1.00 5.196 2.911 [5] δ-phase face-centered cubic, B1 NaCl-type TaN 0.92 4.337 [6] TaN 0.97 4.336 [7] θ-phase hexagonal, Bh WC-type TaN [3] TaN x cubic, CaF 2 -type TaN x 5.02 [11] CaF 2 -type with a body-centered tetragonal superstructure TaN x 5.77 5.01 [12] nitride obtained by Gatterer et al [6] from the elements at 2000°C and a pressure of 40 bar, and that obtained by Mashimo et al [7] (a ϭ 4.336 Å ), are almost identical.…”

Section: Introductionmentioning

confidence: 99%

“…While the earlier studies suggested a statistical distribution, [1,2] electron- [3] and neutron-diffraction [4] investigations revealed a trigonal P31m supercell with aЈ ϭ Ί3a, isostructural to β-Nb 2 N [14] and of the anti-Li 2 ZrF 6 -type. [15] The γ-phase can be obtained by nitriding of tantalum powder in gaseous ammonia at 800Ϫ900°C or from the elements at 2000°C.…”

Section: Introductionmentioning

confidence: 99%

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Plasma‐Enhanced CVD Synthesis and Structural Characterization of Ta₂N₃

2004

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Keywords: Tantalum / Nitrides / Plasma-enhanced chemical vapor deposition / X-ray diffraction / Electron microscopy Microcrystalline tantalum nitride films were prepared on various substrates from TaCl 5 precursor and nitrogen gas using the plasma-enhanced chemical vapor deposition (PECVD) method. Syntheses carried out at 600−650°C led to single-phase samples of the tantalum nitride Ta 2 N 3 with a defect fluorite-type structure. The anion vacancies were found to order resulting in a 2 ϫ 2 ϫ 2 cubic superstructure of the C-Ln 2 O 3 type (space group Ia3 , Z = 16) with a = 9.8205(4) Å according to a Rietveld refinement of the X-ray IntroductionThe binary TaϪN system is quite rich in compounds with well-defined and variable stoichiometries. The formal oxidation state of tantalum covers the whole range from nearly zero to the maximum of ϩ5. These compounds can be divided into four groups: solid solutions of nitrogen in tantalum, the phase with the approximate stoichiometry Ta 2 N, three phases with a nearly 1:1 composition, and nitrogenrich nitrides. A few comprehensive reviews of tantalum nitride structural chemistry are available.[1Ϫ3] Results of the previous structural studies in this binary system are summarized in Table 1.Up to 5 at.% of nitrogen can be dissolved in the bodycentered cubic lattice of elemental tantalum, for example by heating of Ta powder in ammonia at 600Ϫ700°C.[3] The lattice constant of such solid solutions increases slightly to 3.315Ϫ3.369 Å compared to that of the pure metal (a ϭ 3.311 Å ). Observation of additional weak reflections suggests a cubic superstructure with the unit cell tripled in all directions and with a β ϭ 3a α ϭ 10.11 Å . The γ-phase with the composition range TaN 0.41Ϫ0.5 , also denoted as β-Ta 2 N, [4] crystallizes with a hexagonal unit cell.[1Ϫ4] Its crystal structure can be described as a hexagonal close packing of the tantalum atoms with the nitrogen atoms filling half of the octahedral interstices. While the earlier studies suggested a statistical distribution, [1,2] electron- [3] and neutron-diffraction [4] investigations revealed a trigonal P31m supercell with aЈ ϭ Ί3a, isostructural to β-Nb 2 N [14] and of the anti-Li 2 ZrF 6 -type.[15] The γ-phase can be obtained by nitriding of tantalum powder in gaseous ammonia at 800Ϫ900°C or from the elements at 2000°C. [1,3] The hexagonal ε-phase was proposed by Schoenberg [1] to have a B35 CoSn-type structure with the composition TaN 1.00 ; the same description was given by Brauer and Zapp.[2] In this structure type the nitrogen atoms are at the center of slightly distorted tantalum octahedra. Later, Christensen and Lebech [5] showed that the nitrogen atoms are displaced from these ideal positions reducing their coordination sphere to a square pyramid. The unit cell determined by Christensen and Lebech [5] (a ϭ 5.196 Å , c ϭ 2.911 Å ) is quite similar to that given by the other authors.[1Ϫ3] The ε-phase can be obtained as a product of nitriding of Ta powder at temperatures at Ͼ 1100°C. [1] Another modification of tantalum ...

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“…[22] In order to test the reliability of our approach, the first step was to perform an optimization of the cell parameter. For this purpose a cube containing 4 Ti at-oms and 4 N atoms was selected as supercell.…”

Section: Computational Detailsmentioning

confidence: 99%

A First Principles Density Functional Study of Au Deposition on TiN (001) Surface

Hernández

Sanz

2001

IJMS

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Abstract:The structure and local electron properties of Au atoms deposited on the TiN (001) surface has been theoretically analyzed using a periodic slab model and density functional based calculations. The surface is described by means of a 2x2 cell five layers thick, on which gold atoms are added. Deposition of single atoms on the surface, (θ = 0.25 ML),shows that the preferred site is on-top of Ti atoms, with a metal-surface distance of 2.49 Å.The computed adsorption energy for this site is -1.92 eV, only slightly lower than that lying between two Ti surface atoms (-1.90 eV). The on-top nitrogen sites are less favorable by about 0.4 eV. The calculations were carried out using the Perdew-Wang 91 exchange correlation functional and ultra soft pseudopotentials, with electronic states represented by a plane-wave expansion.

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Some Features of the Nb-N and Nb-N-O Systems.

Cited by 98 publications

References 0 publications

First-principles calculations of mechanical properties of TiC and TiN

First-principles calculations of mechanical properties of TiC and TiN

Plasma‐Enhanced CVD Synthesis and Structural Characterization of Ta₂N₃

A First Principles Density Functional Study of Au Deposition on TiN (001) Surface

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Some Features of the Nb-N and Nb-N-O Systems.

Cited by 98 publications

References 0 publications

First-principles calculations of mechanical properties of TiC and TiN

First-principles calculations of mechanical properties of TiC and TiN

Plasma‐Enhanced CVD Synthesis and Structural Characterization of Ta2N3

A First Principles Density Functional Study of Au Deposition on TiN (001) Surface

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Plasma‐Enhanced CVD Synthesis and Structural Characterization of Ta₂N₃