Bonding mechanism in the nitrides<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mi mathvariant="normal">Ti</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:mi mathvariant="normal">Al</mml:mi><mml:mi mathvariant="normal">N</mml:mi></mml:mrow></mml:math>and TiN: An experimental and theoretical investigation

Magnuson, Martin; Mattesini, Maurizio; Li, S.; Höglund, Carina; Beckers, Markus; Hultman, Lars; Eriksson, Olle

doi:10.1103/physrevb.76.195127

Cited by 71 publications

(58 citation statements)

References 46 publications

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“…For the Ti L 2,3 SXE spectra of nc-TiC/a-C, the main L 3 peak observed at −2.1 eV is due to Ti 3d-C 2p hybridization while the weak shoulder at −10 eV is due to Ti 3d-C 2s hybridization. 34,35 The small L 2 emission line is found at +5.2 eV for Ti metal and +4.1 eV for the nc-TiC/a-C relative to the E F of the 2p 3/2 component. The low-energy shift ͑−1.1 eV͒ and the increased broadening of the L 3 and L 2 peaks for decreasing grain size are an indication of stronger Ti 3d-C 2p interaction and bonding than for the more well-defined Ti 3d-Ti 3d hybridization region in Ti metal.…”

Section: Ti L 23 X-ray Emissionmentioning

confidence: 99%

Electronic structure and chemical bonding of nanocrystalline-TiC/amorphous-C nanocomposites

et al. 2009

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The electronic structure of nanocrystalline ͑nc-͒ TiC/amorphous C nanocomposites has been investigated by soft x-ray absorption and emission spectroscopy. The measured spectra at the Ti 2p and C 1s thresholds of the nanocomposites are compared to those of Ti metal and amorphous C. The corresponding intensities of the electronic states for the valence and conduction bands in the nanocomposites are shown to strongly depend on the TiC carbide grain size. An increased charge transfer between the Ti 3d-e g states and the C 2p states has been identified as the grain size decreases, causing an increased ionicity of the TiC nanocrystallites. It is suggested that the charge transfer occurs at the interface between the nanocrystalline-TiC and the amorphous-C matrix and represents an interface bonding which may be essential for the understanding of the properties of nc-TiC/amorphous C and similar nanocomposites.

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Section: Ti L 23 X-ray Emissionmentioning

confidence: 99%

Electronic structure and chemical bonding of nanocrystalline-TiC/amorphous-C nanocomposites

et al. 2009

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“…Ti 2 AlN has also been synthesized using reactive sputtering in N 2 from Ti and Al elemental targets [129,146,147,148]. These publications contain the explanation for why relatively little work has been devoted to reactive sputter deposition of MAX phases, and why sputter-deposition of MAX nitrides is much less explored than the carbides: the process window (with respect to N 2 partial pressure) for deposition of single-phase Ti 2 AlN is extremely narrow [129,145].…”

Section: Reactive Sputteringmentioning

confidence: 99%

The M+1AX phases: Materials science and thin-film processing

et al. 2010

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This article is a critical review of the M n+1 AX n phases ("MAX phases", where n =1, 2, or 3) from a materials science perspective. MAX phases are a class of hexagonal-structure ternary carbides and nitrides ("X") of a transition metal ("M") and an A-group element. The most well known are Ti 2 AlC, Ti 3 SiC 2 , and Ti 4 AlN 3 . There are ~60 MAX phases with at least 9 discovered in the last five years alone. What makes the MAX phases fascinating and potentially useful is their remarkable combination of chemical, physical, electrical, and mechanical properties, which in many ways combine the characteristics of metals and ceramics. For example, MAX phases are typically resistant to oxidation and corrosion, elastically stiff, but at the same time they exhibit high thermal and electrical conductivities and are machinable. These properties stem from an inherently nanolaminated crystal structure, with M n+1 X n slabs intercalated with pure A-element layers. The research on MAX phases has been accelerated by the introduction of thin-film processing methods.Magnetron sputtering and arc deposition have been employed to synthesize single-crystal material by epitaxial growth, which enables studies of fundamental materials properties. However, the surface-initiated decomposition of M n+1 AX n thin films into MX compounds at temperatures of 1000-1100 °C is much lower than the decomposition temperatures typically reported for the corresponding bulk material. We also review the prospects for low-temperature synthesis, which is essential for deposition of MAX phases onto technologically important substrates. While deposition of MAX phases from the archetypical Ti-Si-C and Ti-Al-N systems typically require synthesis temperatures of ~800 °C, recent results have demonstrated that V 2 GeC and Cr 2 AlC can be deposited at ~450 °C. Also, thermal spray of Ti 2 AlC powder has been used to produce thick coatings. We further treat progress in the use of first-principles calculations for predicting hypothetical MAX phases and their properties. Together with advances in processing and materials 3 analysis, this progress has led to recent discoveries of numerous new MAX phases such as Ti 4 SiC 3 , Ta 4 AlC 3 , and Ti 3 SnC 2 . Finally, important future research directions are discussed. These include charting the unknown regions in phase diagrams to discover new equilibrium and metastable phases, as well as research challenges in understanding their physical properties, such as the effects of anisotropy, impurities, and vacancies on the electrical properties, and unexplored properties such as superconductivity, magnetism, and optics. 4

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“…[1][2][3][4][5][6] Also, the electronic properties of these materials have been studied both theoretically and experimentally. [4][5][6][7][8][9] For MAX-phases in thin film form, the processing and physical properties have been recently reviewed. 10 Because the MAX-phases crystallize in a hexagonal structure the anisotropy of its conductivity is of great interest but it has been difficult to experimentally resolve this issue.…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic ellipsometry study on the dielectric function of bulk Ti2AlN, Ti2AlC, Nb2AlC, (Ti0.5,Nb0.5)2AlC, and Ti3GeC2 MAX-phases

Mendoza-Galván¹,

Rybka²,

Järrendahl³

et al. 2011

Journal of Applied Physics

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The averaged complex dielectric function = ͑2 Ќ + ʈ ͒ / 3 of polycrystalline Ti 2 AlN, Ti 2 AlC, Nb 2 AlC, ͑Ti 0.5 ,Nb 0.5 ͒ 2 AlC, and Ti 3 GeC 2 was determined by spectroscopic ellipsometry covering the mid infrared to the ultraviolet spectral range. The dielectric functions Ќ and ʈ correspond to the perpendicular and parallel dielectric tensor components relative to the crystallographic c-axis of these hexagonal compounds. The optical response is represented by a dispersion model with DrudeLorentz and critical point contributions. In the low energy range the electrical resistivity is obtained from the Drude term and ranges from 0.48 ⍀ m for Ti 3 GeC 2 to 1.59 ⍀ m for ͑Ti 0.5 ,Nb 0.5 ͒ 2 AlC. Furthermore, several compositional dependent interband electronic transitions can be identified. For the most important ones, Im͑ ͒ shows maxima at: 0.78, 1.23, 2.04, 2.48, and 3.78 eV for Ti 2 AlN; 0.38, 1.8, 2.6, and 3.64 eV for Ti 2 AlC; 0.3, 0.92, and 2.8 eV in Nb 2 AlC; 0.45, 0.98, and 2.58 eV in ͑Ti 0.5 ,Nb 0.5 ͒ 2 AlC; and 0.8, 1.85, 2.25, and 3.02 eV in Ti 3 GeC 2 .

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Bonding mechanism in the nitridesTi2AlNand TiN: An experimental and theoretical investigation

Cited by 71 publications

References 46 publications

Electronic structure and chemical bonding of nanocrystalline-TiC/amorphous-C nanocomposites

Electronic structure and chemical bonding of nanocrystalline-TiC/amorphous-C nanocomposites

The M+1AX phases: Materials science and thin-film processing

Spectroscopic ellipsometry study on the dielectric function of bulk Ti2AlN, Ti2AlC, Nb2AlC, (Ti0.5,Nb0.5)2AlC, and Ti3GeC2 MAX-phases

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