Vacancy-induced toughening in hard single-crystal V 0.5 Mo 0.5 N x /MgO(0 0 1) thin films

Kindlund, Hanna; Sangiovanni, Davide; Lu, Jun; Jensen, Jens; Chirita, Valeriu; Birch, Jens; Petrov, I.; Greene, J. E.; Hultman, Lars

doi:10.1016/j.actamat.2014.06.025

Cited by 82 publications

(65 citation statements)

References 35 publications

(41 reference statements)

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“…NaCl-structure (B1) TiN is a model system for transition-metal (TM) nitrides, a class of technologically important ceramic materials characterized by outstanding combinations of mechanical [23][24][25][26][27], physical [28,29], optical [30,31], electrical [32], and catalytic properties [33,34]. In addition, the properties can be tuned by varying TM compositions in alloys [32,[35][36][37][38] and/or the N/TM ratio [39][40][41][42][43] over wide ranges while preserving the cubic phase. AIMD simulations were used to separately determine the effects of varying the island area and temperature on adatom mobilities, as well as on Ti ad interlayer migration rates.…”

Section: Introductionmentioning

confidence: 99%

Effects of surface vibrations on interlayer mass transport: Ab initio molecular dynamics investigation of Ti adatom descent pathways and rates from TiN/TiN(001) islands

et al. 2018

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We carried out density-functional ab initio molecular dynamics (AIMD) simulations of Ti adatom (Ti ad ) migration on, and descent from, square TiN 100 epitaxial islands on TiN(001) at temperatures (T ) ranging from 1200 to 2400 K. Adatom-descent energy barriers determined via ab initio nudged-elastic-band calculations at 0 Kelvin suggest that Ti interlayer transport on TiN(001) occurs essentially exclusively via direct hopping onto a lower layer. However, AIMD simulations reveal comparable rates for Ti ad descent via direct hopping vs push-out/exchange with a Ti island-edge atom for T 1500 K. We demonstrate that this effect is due to surface vibrations, which yield considerably lower activation energies at finite temperatures by significantly modifying the adatom push-out/exchange reaction pathway.

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Section: Introductionmentioning

confidence: 99%

Effects of surface vibrations on interlayer mass transport: Ab initio molecular dynamics investigation of Ti adatom descent pathways and rates from TiN/TiN(001) islands

et al. 2018

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“…Kinetic control of (N/TM) ratios during crystal growth is exploited to tune the structural [19,20], electrical [21,22], optical [23,24], and mechanical properties [25][26][27] of these ceramics. Hence, clarification of the mechanisms governing vacancy formation and evaluation of vacancy diffusivities as a function of temperature may allow determining optimal synthesis conditions to deposit TM nitride thin films with desired properties.…”

Section: Introductionmentioning

confidence: 99%

Nonequilibrium ab initio molecular dynamics determination of Ti monovacancy migration rates in B1 TiN

et al. 2017

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We use the color diffusion (CD) algorithm in nonequilibrium (accelerated) ab initio molecular dynamics simulations to determine Ti monovacancy jump frequencies in NaCl-structure titanium nitride (TiN), at temperatures ranging from 2200 to 3000 K. Our results show that the CD method extended beyond the linear-fitting rate-versus-force regime [Sangiovanni et al., Phys. Rev. B 93, 094305 (2016)] can efficiently determine metal vacancy migration rates in TiN, despite the low mobilities of lattice defects in this type of ceramic compound. We propose a computational method based on gamma-distribution statistics, which provides unambiguous definition of nonequilibrium and equilibrium (extrapolated) vacancy jump rates with corresponding statistical uncertainties. The acceleration-factor achieved in our implementation of nonequilibrium molecular dynamics increases dramatically for decreasing temperatures from 500 for T close to the melting point T m , up to 33 000 for T ≈ 0.7 T m .

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“…Due to excellent physical and mechanical properties, including high hardness [1][2][3] and toughness [4,5], chemical inertness [6], thermal stability [7], and good electrical conductivity [3], transition metal (TM) nitrides are widely applied as wear-resistant protective coatings for cutting tools [8] and engine components [9] and as diffusion barriers in electronic devices [10,11]. The properties and performances of TM nitride thin films depend on their micro-and nanostructure.…”

Section: Introductionmentioning

confidence: 99%

Nitrogen vacancy, self-interstitial diffusion, and Frenkel-pair formation/dissociation inB1TiN studied byab initioand classical molecular dynamics with optimized potentials

et al. 2015

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We use ab initio and classical molecular dynamics (AIMD and CMD) based on the modified embedded-atom method (MEAM) potential to simulate diffusion of N vacancy and N self-interstitial point defects in B1 TiN. TiN MEAM parameters are optimized to obtain CMD nitrogen point-defect jump rates in agreement with AIMD predictions, as well as an excellent description of TiN x (∼0.7 < x 1) elastic, thermal, and structural properties. We determine N dilute-point-defect diffusion pathways, activation energies, attempt frequencies, and diffusion coefficients as a function of temperature. In addition, the MD simulations presented in this paper reveal an unanticipated atomistic process, which controls the spontaneous formation of N self-interstitial/N vacancy (N I /N V ) pairs (Frenkel pairs), in defect-free TiN. This entails that the N lattice atom leaves its bulk position and bonds to a neighboring N lattice atom. In most cases, Frenkel-pair N I and N V recombine within a fraction of ns; ∼50% of these processes result in the exchange of two nitrogen lattice atoms (N−N Exc ). Occasionally, however, Frenkel-pair N-interstitial atoms permanently escape from the anion vacancy site, thus producing unpaired N I and N V point defects.

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Vacancy-induced toughening in hard single-crystal V 0.5 Mo 0.5 N x /MgO(0 0 1) thin films

Cited by 82 publications

References 35 publications

Effects of surface vibrations on interlayer mass transport: Ab initio molecular dynamics investigation of Ti adatom descent pathways and rates from TiN/TiN(001) islands

Effects of surface vibrations on interlayer mass transport: Ab initio molecular dynamics investigation of Ti adatom descent pathways and rates from TiN/TiN(001) islands

Nonequilibrium ab initio molecular dynamics determination of Ti monovacancy migration rates in B1 TiN

Nitrogen vacancy, self-interstitial diffusion, and Frenkel-pair formation/dissociation inB1TiN studied byab initioand classical molecular dynamics with optimized potentials

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