Self‐diffusion in nickel at low temperatures

Maier, K.; Mehrer, H.; Lessmann, E.; Schüle, W.

doi:10.1002/pssb.2220780230

Cited by 206 publications

(75 citation statements)

References 25 publications

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“…Unlike Ni foam templates with unit cell sizes of the order of hundreds of microns, 1 the sub-micron unit cells of Ni gyroid templates transform into bulky clusters at temperatures >500 o C. The formation of clusters is driven by the thermodynamic tendency to minimise the surface area, enabled by the increase in Ni self-diffusion with temperature. 37 Using a typical one-step CVD process, 18 where the hydrocarbon precursor is introduced only once the growth temperature has been reached, both G35_Ni and G60_Ni do not preserve their original morphologies and transform into large clusters already during the heating ramp (Fig. 4a).…”

Section: Fig 3 (A) Raman Spectra Of: Graphene On a 500 Nm Thick Ni mentioning

confidence: 99%

“…The suitability of a given metal template will depend on its catalytic efficiency to induce graphitisation compared to its self-diffusivity at the given CVD temperature. Hence the temperature instabilities of sub-micron unit cell structures can be similarly addressed for metals that in those respects show a similar behaviour to Ni, 37 such as Co, 43 or for metals, that require higher growth temperatures but have lower self-diffusivities, such as Pt. [44][45][46] For metals, such as Cu, that require higher temperatures for graphene growth and have high self-diffusivities (3 orders of magnitude higher for Cu than Ni at 900 °C), 47,48 successfully applying our approach may be more challenging.…”

Section: Fig 3 (A) Raman Spectra Of: Graphene On a 500 Nm Thick Ni mentioning

confidence: 99%

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Chemical vapour deposition of freestanding sub-60 nm graphene gyroids

Cebo

Aria

Dolan

et al. 2017

Applied Physics Letters

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The direct chemical vapour deposition (CVD) of freestanding graphene gyroids with controlled sub-60 nm unit cell sizes is demonstrated. Three-dimensional (3D) nickel templates were fabricated through electrodeposition into a selectively voided triblock terpolymer. The high temperature instability of sub-micron unit cell structures was effectively addressed through the early introduction of carbon precursor, which stabilizes the metallized gyroidal templates. The as-grown graphene gyroids are self-supporting and can be transferred onto a variety of substrates. Furthermore they represent the smallest free standing graphene 3D structures yet produced with a pore size of tens of nm, as analysed by electron microscopy and optical spectroscopy. We discuss the generality of our methodology for the synthesis of other types of nanoscale, 3D graphene assemblies and the transferability of this approach to other 2D materials.

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Section: Fig 3 (A) Raman Spectra Of: Graphene On a 500 Nm Thick Ni mentioning

confidence: 99%

Section: Fig 3 (A) Raman Spectra Of: Graphene On a 500 Nm Thick Ni mentioning

confidence: 99%

Chemical vapour deposition of freestanding sub-60 nm graphene gyroids

Cebo

Aria

Dolan

et al. 2017

Applied Physics Letters

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“…At SOFC operating temperatures, the bulk self-diffusion for metals typically used in SOFC anodes $ 10 À16 m 2 s À1 [22], whereas for surface self-diffusion of these metals D s $ 10 À11 m 2 s À1 [23]. It is also worth noting that the Zr 4þ surface diffusion coefficient in YSZ is $ 10 À18 m 2 s À1 [24].…”

Section: Diffuse-interface Formalismmentioning

confidence: 99%

Phase wettability and microstructural evolution in solid oxide fuel cell anode materials

et al. 2014

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Recent experimental and theoretical findings suggest that high-temperature solid oxide fuel cells (SOFCs) often suffer from performance degradation due to coarsening of the metallic-phase particles within the anode. In this study, we explore the feasibility of improving the microstructural stability of SOFC anode materials by tuning the contact angle between the metallic phase and electrolyte particles. To this end, a continuum diffuse-interface model is employed to capture the coarsening behavior of the metallic phase and simulate a range of equilibrium contact angles. The evolution of performance-critical, microstructural features is presented for varying degrees of phase wettability. It is found that both the density of electrochemically active triple-phase regions and contiguity of the electron-conducting phase display undesirable minima near the contact angle of conventional SOFC materials. Our results suggest that tailoring the interfacial properties of the constituent phases could lead to a significant increase in the performance and lifetime of SOFCs.

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“…This value was found to be on the order of 10 -5 m 2 /s for the dilute diffusion of transition metals in Ni [2,31]. Thus, 10 -5 m 2 /s will be used for the diffusion prefactor in this work as an approximation, a value that well represents the experimental diffusion prefactor of pure Ni (8.5×10 -5 -17.7×10 -5 m 2 /s [33][34][35]). …”

Section: Diffusion Coefficient Calculationmentioning

confidence: 89%

Effects of Alloying Elements on Elastic, Stacking Fault and Diffusion Properties of Fcc Ni from First-principles: Implications for Tailoring the Creep Rate of Ni-base Superalloys

Zacherl¹,

Shang²,

Kim³

et al. 2012

Superalloys 2012 (Twelfth International Symposium)

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To understand the effects of alloying elements on the creep rate of Ni-base superalloys, factors entering into a secondary creep rate are calculated via first-principles calculations based on density functional theory for 26 Ni 31 X systems where X = Al, Co, Cr, Cu, Fe, Hf, Ir, Mn, Mo, Nb, Os, Pd, Pt, Re, Rh, Ru, Sc, Si, Ta, Tc, Ti, V, W, Y, Zr, and Zn. They are volume, elastic properties, stacking fault energy, and diffusivity. It is found that shear modulus, Young's modulus, and roughly stacking fault energy show inverse correlation to the atomic volume of the system. In addition, the closer the alloying elements to Ni, with respect to atomic volume and atomic number, the larger the predicted shear modulus, Young's modulus, and stacking fault energy. Diffusivity calculations show that mid-row 5d transition metal elements, particularly Re, Os, and Ir, have the highest activation barrier for diffusion, while far-right or far-left row placement elements such as Y, Zn, and Hf, have the lowest activation energy barriers for diffusion. A creep rate ratio of ߝሶ ே యభ ߝሶ ே ⁄ is calculated and the effect of the alloying elements shows 13 systems have a decreased creep rate relative to Ni, while 13 systems have an increased creep rate relative to Ni.

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Self‐diffusion in nickel at low temperatures

Cited by 206 publications

References 25 publications

Chemical vapour deposition of freestanding sub-60 nm graphene gyroids

Chemical vapour deposition of freestanding sub-60 nm graphene gyroids

Phase wettability and microstructural evolution in solid oxide fuel cell anode materials

Effects of Alloying Elements on Elastic, Stacking Fault and Diffusion Properties of Fcc Ni from First-principles: Implications for Tailoring the Creep Rate of Ni-base Superalloys

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