Elastic constants of epitaxial cubic MoN (001) layers

Ozsdolay, B.D.; Shen, Xin; Balasubramanian, Karthik; Scannell, Garth; Huang, Liping; Yamaguchi, Masashi; Gall, Daniel

doi:10.1016/j.surfcoat.2017.07.015

Cited by 23 publications

(12 citation statements)

References 89 publications

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“…A similar trend is found for the film series deposited at 500°C, the C 44 values being systematically higher by 8-10 GPa. For MoN 0.75 epitaxial layer, Ozsdolay et al 65 measured a value of C 44 = 86 GPa, which is 37% lower than the value obtained for our binary MoN 0.75 film (C 44 = 136 GPa). However, in their study, the layers were deposited at a much higher working pressure (2.67 Pa), resulting in underdense layers (20% lower density compared to our films), which can explain their lower shear elastic constant, as well as a difference in the respective defects content.…”

Section: Elastic and Mechanical Propertiescontrasting

confidence: 81%

“…A similar evolution is also noticed for the T s = 500°C film series, albeit V T values being systematically higher by 3%-5%. For x = 0, the value reported by Ozsdolay et al 65 for the MoN 0.75 epitaxial layer on MgO (001) is V T = 3.32 km/s, which is ∼10% lower than values for our binary MoN ∼0.75 films. The evolution of shear elastic constant C 44 with Al fraction is displayed in Fig.…”

Section: Elastic and Mechanical Propertiescontrasting

confidence: 74%

“…This is an indication that the higher substrate temperature favors a slightly lower N concentration (due to desorption), as also reported by Ozsdolay et al for MoN y films. 22,65 It can be also anticipated that higher T s would also favor defect annihilation, especially point defect of interstitial type created by energetic particle bombardment, 42 which would also contribute to a 0 shrinkage.…”

Section: B Chemical and Structural Propertiesmentioning

confidence: 99%

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Structure, stress, and mechanical properties of Mo-Al-N thin films deposited by dc reactive magnetron cosputtering: Role of point defects

Anğay

Löfler

Têtard

et al. 2020

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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In this work, the structural and mechanical properties of ternary Mo-Al-N alloys are investigated by combining thin film growth experiments and density functional theory (DFT) calculations. Mo 1−x Al x N y thin films (∼300 nm thick), with various Al fractions ranging from x = 0 to 0.5 and nitrogen-to-metal (Al + Mo) ratio ranging from y = 0.78 to 1.38, were deposited by direct-current reactive magnetron cosputtering technique from elemental Mo and Al targets under Ar + N 2 plasma discharges. The Al content was varied by changing the respective Mo and Al target powers, at a fixed N 2 (20 SCCM) and Ar (25 SCCM) flow rate, and using two different substrate temperatures T s = 350 and 500°C. The elemental composition, mass density, crystal structure, residual stress state, and intrinsic (growth) stress were examined by wavelength dispersive x-ray spectroscopy, x-ray reflectivity, x-ray diffraction, including pole figure and sin 2 ψ measurements, and real-time in situ wafer curvature. Nanoindentation tests were carried out to determine film hardness H and elastic modulus E IT , while the shear elastic constant C 44 was measured selectively by surface Brillouin light spectroscopy. All deposited Mo 1−x Al x N y films have a cubic rock-salt crystal structure and exhibit a fiber-texture with a [001] preferred orientation. The incorporation of Al is accompanied by a rise in nitrogen content from 44 to 58 at. %, resulting in a significant increase (2%) in the lattice parameter when x increases from 0 to 0.27. This trend is opposite to what DFT calculations predict for cubic defect-free stoichiometric Mo 1−x Al x N compounds and is attributed to variation in point defect concentration (nitrogen and metal vacancies) when Al substitutes for Mo. Increasing T s from 350 to 500°C has a minimal effect on the structural properties and phase composition of the ternary alloys but concurs to an appreciable reduction of the compressive stress from −5 to −4 GPa. A continuous increase and decrease in transverse sound velocity and mass density, respectively, lead to a moderate stiffening of the shear elastic constant from 130 to 144 GPa with increasing Al fraction up to x = 0.50, and a complex and nonmonotonous variation of H and E IT is observed. The maximum hardness of ∼33 GPa is found for the Mo 0.81 Al 0.19 N 1.13 film, with nitrogen content close to the stoichiometric composition. The experimental findings are explained based on structural and elastic constant values computed from DFT for defect-free and metal-or nitrogen-deficient rock-salt MoAlN compounds.

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Section: Elastic and Mechanical Propertiescontrasting

confidence: 81%

Section: Elastic and Mechanical Propertiescontrasting

confidence: 74%

Section: B Chemical and Structural Propertiesmentioning

confidence: 99%

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Structure, stress, and mechanical properties of Mo-Al-N thin films deposited by dc reactive magnetron cosputtering: Role of point defects

Anğay

Löfler

Têtard

et al. 2020

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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“…Uakitite, obtained from a meteorite found in the Baunt Evenk district, Republic of Buryatia, near Zabaykalsky Krai (Eastern Siberia), Russia, was recently reported at the Annual Meeting of the Meteoritical Society in Moscow, July 22-27 (2018) [129] is an antiferromagnetic orthorhombic phase, which becomes paramagnetic B1 at room temperature [130]. MoN and WN, both mechanically unstable in defect-free B1 structures [123], can be stabilized in the NaCl phase by lattice vacancies [131][132][133][134][135]. Furthermore, the occurrence of an antiferromagnetic (0 K) → paramagnetic (room temperature) transition has recently been found in understoichiometric B1 MoNx [136].…”

Section: Groups 4 5 and 6 Tm Nitrides: An Overview Of Fundamental Propertiesmentioning

confidence: 99%

A review of the intrinsic ductility and toughness of hard transition-metal nitride alloy thin films

et al. 2019

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Over the past decades, enormous effort has been dedicated to enhancing the hardness of refractory ceramic materials. Typically, however, an increase in hardness is accompanied by an increase in brittleness, which can result in intergranular decohesion when materials are exposed to high stresses. In order to avoid brittle failure, in addition to providing high strength, films should also be ductile, i.e., tough. However, fundamental progress in obtaining hard-yet-ductile ceramics has been slow since most toughening approaches are based on empirical trial-and-error methods focusing on increasing the strength and ductility extrinsically, with a limited focus on understanding thin-film toughness as an inherent physical property of the material. Thus, electronic structure investigations focusing on the origins of ductility vs. brittleness are essential in understanding the physics behind obtaining both high strength and high plastic strain in ceramics films. Here, we review recent progress in experimental validation of density functional theory predictions on toughness enhancement in hard ceramic films, by increasing the valence electron concentration, using examples from the V1-xWxN and V1-xMoxN alloy systems.

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“…A wide range of techniques is available to investigate the elastic properties of coatings; namely, nanoindentation [2,3] and various acoustic based techniques [4], including Brillouin spectroscopy [5,6,7,8], while little is known about the CTE of films. The standard techniques adopted to measure the CTE of bulk materials (e.g.…”

Section: Introductionmentioning

confidence: 99%

Coefficient of thermal expansion of nanostructured tungsten based coatings assessed by substrate curvature method

et al. 2018

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The in plane coefficient of thermal expansion (CTE) and the residual stress of nanostructured W based coatings are extensively investigated. The CTE and the residual stresses are derived by means of an optimized ad-hoc developed experimental setup based on the detection of the substrate curvature by a laser system. The nanostructured coatings are deposited by Pulsed Laser Deposition. Thanks to its versatility, nanocrystalline W metallic coatings, ultra-nano-crystalline pure W and W-Tantalum coatings and amorphous-like W coatings are obtained. The correlation between the nanostructure, the residual stress and the CTE of the coatings are thus elucidated. We find that all the samples show a compressive state of stress that decreases as the structure goes from columnar nanocrystalline to amorphous-like. The CTE of all the coatings is higher than the one of the corresponding bulk W form. In particular, as the grain size shrinks, the CTE increases from 5

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Elastic constants of epitaxial cubic MoN (001) layers

Cited by 23 publications

References 89 publications

Structure, stress, and mechanical properties of Mo-Al-N thin films deposited by dc reactive magnetron cosputtering: Role of point defects

Structure, stress, and mechanical properties of Mo-Al-N thin films deposited by dc reactive magnetron cosputtering: Role of point defects

A review of the intrinsic ductility and toughness of hard transition-metal nitride alloy thin films

Coefficient of thermal expansion of nanostructured tungsten based coatings assessed by substrate curvature method

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