Crystal structure of molybdenum nitride films made by reactive cathodic arc evaporation

Perry, A.J.; Baouchi, A.Wahab; Petersen, J.H.; Pozder, S.

doi:10.1016/s0257-8972(09)90060-3

Cited by 34 publications

(17 citation statements)

References 16 publications

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“…I, PVD allows to prepare metastable n-MoN (Fm-3 m), 17 if the ionization degree and/or the nitrogen partial pressure is very high. This metastable phase is based on the stable high-temperature phase fcc c-Mo 2 N (Fm-3 m), 14,40 but with (theoretically) fully occupied octahedral sites of the fcc structure formed by Mo.…”

Section: Discussionmentioning

confidence: 99%

“…16 For extremely high nitrogen pressures, even the metastable n-MoN (Fm-3 m) is accessible. 17 However, the formation of interatomic bonds in Mo-N, by filling of antibonding electron states, results in low chemical and thermal stability. 18 Therefore, we use the concept of alloying Mo-N with Cr, to increase the chemical and thermal stability.…”

Section: Introductionmentioning

confidence: 99%

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Composition driven phase evolution and mechanical properties of Mo–Cr–N hard coatings

Klimashin

Riedl

Primetzhofer

et al. 2015

Journal of Applied Physics

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Although many research activities concentrate on transition metal nitrides, due to their excellent properties, only little is known about Mo–N based materials. We investigate in detail the influence of Cr on the structural evolution and mechanical properties of Mo–N coatings prepared at different nitrogen partial pressures. The chemical composition as well as the structural development of coatings prepared with N2-to-total pressure ratios (pN2/pT) of 0.32 and 0.44 can best be described by the quasi-binary Mo2N–CrN tie line. Mo2N and CrN are face centered cubic (fcc), only that for Mo2N half of the N-sublattice is vacant. Consequently, with increasing Cr content, also the N-sublattice becomes less vacant and the chemical composition of fcc single-phase ternaries can be described as Mo1−xCrxN0.5(1+x). These coatings exhibit an excellent agreement between experimentally and ab initio obtained lattice parameters of fcc Mo1−xCrxN0.5(1+x). When increasing the N2-to-total pressure ratio to pN2/pT = 0.69, the N-sublattice is already fully occupied for Cr-additions of x ≥ 0.4, as suggested by elastic recoil detection analysis and lattice parameter variations. The latter follows the ab initio obtained lattice parameters along the quasi-binary MoN–CrN tie line for x ≥ 0.5. The single-phase fcc coating with Cr/(Mo+Cr) of x ∼0.2, prepared with pN2/pT = 0.32, exhibits the highest hardness of ∼34 GPa among all coatings studied.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Composition driven phase evolution and mechanical properties of Mo–Cr–N hard coatings

Klimashin

Riedl

Primetzhofer

et al. 2015

Journal of Applied Physics

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“…The Mo-N system has been reported to crystallize in various phases, with the most common being (i) BCC Mo with a possible small amount of dissolved nitrogen, (ii) facecentered cubic γ-Mo 2 N x , (iii) body-centered tetragonal β-Mo 2 N x , and (iv) hexagonal δ-MoN [23][24][25][26][27]. Interestingly, the β and γ phases have nominally the same composition range, with some experiments reporting the γ and β phase forming below and above a critical temperature of 775 °C [28], in apparent contradiction to the reported Mo-N phase diagram which suggests γ to be the high-temperature phase and β the low-temperature phase [29].…”

Section: Introductionmentioning

confidence: 99%

Cation and anion vacancies in cubic molybdenum nitride

Ozsdolay

Balasubramanian

Gall

2017

Journal of Alloys and Compounds

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Epitaxial MoN x layers deposited on MgO(001) by reactive magnetron sputtering in 20 mTorr N 2 at T s = 600-1000 °C exhibit a cubic rock-salt type structure, a N-to-Mo ratio that decreases from x = 1.25-0.69 with increasing T s , and a lattice constant that simultaneously decreases from 4.26-4.16 Å. A combination of composition, thickness, lattice-constant, and atomic area-density measurements indicate that the rock-salt structure contains both anion and cation vacancies, with the Mo site occupancy Χ Mo decreasing from 0.89±0.06 to 0.70±0.04 while the N site occupancy Χ N increases from 0.60±0.04 to 0.88±0.04, as x increases from 0.69-1.25. Density functional calculations for over 200 cubic MoN x configurations confirm the energetic stability of both cation and anion vacancies and predict Χ Mo to decrease from 1.00 to 0.67 for x = 0.54-1.50, while Χ N increases from 0.50 to 1.00 for x = 0.50-1.36. The simulations are in good agreement with experiments and indicate a preference for a 75% site occupancy on both sublattices for compositions near stoichiometry, with Χ Mo = 0.75 for x = 1.00-1.22 and Χ N = 0.75 for x = 0.86-1.00. Correspondingly, cubic stoichiometric MoN is most stable in the NbO structure.

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“…with increasing nitrogen contents (MoN x , 0.9 < x < 1.3) was already reported by Linker et al [1] and by Perry et al [27]. The 50% vacant octahedral sites of γ-Mo 2 N phase may be preferential occupied by the excess of nitrogen, but the nitrogen atoms may also occupy interstitial sites, resulting in the lattice expansion [2].…”

Section: Structural Propertiesmentioning

confidence: 62%

Properties of MoNxOy thin films as a function of the N/O ratio

et al. 2006

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The main purpose of this work consists on the preparation of single layered molybdenum oxynitride, MoN x O y . The films were deposited on steel substrates by dc reactive magnetron sputtering. The depositions were carried out from a pure Mo target varying the flow rate of reactive gases, which allowed tune the crystallographic structure between insulating oxides and metallic nitrides and consequently electronic, mechanical and optical properties of the material. X-ray diffraction (XRD) results revealed the occurrence of molybdenum nitride for the films with low oxygen fraction: face-centred cubic phases (γ-Mo 2 N) for low nitrogen flow rate or cubic MoN x and hexagonal phase (δ-MoN) for high nitrogen flow rate. The increase of oxygen content induces an amorphization of the nitride phases and appearance of MoO 3 phases. The increase of the oxygen fraction in the films induces also a high decrease in films hardness. Residual stresses revealed to be of compressive type, in the range of very few tenths of GPa to -2 GPa. All these results have been analysed and will be presented as a function of the deposition parameters, the chemical composition and the structure of the films.2

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Crystal structure of molybdenum nitride films made by reactive cathodic arc evaporation

Cited by 34 publications

References 16 publications

Composition driven phase evolution and mechanical properties of Mo–Cr–N hard coatings

Composition driven phase evolution and mechanical properties of Mo–Cr–N hard coatings

Cation and anion vacancies in cubic molybdenum nitride

Properties of MoNxOy thin films as a function of the N/O ratio

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