Size effect of thermal expansion and thermal/intrinsic stresses in nanostructured thin films: Experiment and model

Daniel, Rostislav; Holec, David; Bartosik, Matthias; Keckes, Jozef; Mitterer, Christian

doi:10.1016/j.actamat.2011.07.018

Cited by 85 publications

(44 citation statements)

References 22 publications

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“…The annealing process itself has been monitored in real time with high resolution in-situ curvature measurements, both in order to compare the hydriding properties of the annealed films with as-deposited specimens exhibiting the same initial internal stress state, and to correlate the stress evolution with defect recovery. Many authors indeed identified direct relationships between the stress evolution during annealing and the density of grain boundaries [31,32], point defects [33,34] and dislocations [31,34,35]. The twin concentration can also be expected to be affected by annealing [36,37], but should not give rise to volume changes, and hence to stress changes, although it is expected to affect the hydriding behaviour.…”

Section: Introductionmentioning

confidence: 92%

Effect of structural defects on the hydriding kinetics of nanocrystalline Pd thin films

Delmelle

Amin-Ahmadi

Sinnaeve

et al. 2015

International Journal of Hydrogen Energy

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MicrostructureInternal stress a b s t r a c t While the microstructure of a metal is well-known to affect its equilibrium hydrogen uptake and therefore the hydriding thermodynamics, microstructural effects on the hydriding kinetics are much less documented. Moreover, for thin film systems, such microstructural effects are difficult to separate from the internal stress effect, since most defects generate internal stresses. Such a decoupling has been achieved in this paper for nanocrystalline Pd thin film model systems through the use of a high-resolution, in-situ curvature measurement set-up during Pd deposition, annealing and hydriding. This set-up allowed producing Pd thin films with similar internal stress levels but significantly different microstructures. This was evidenced from detailed defect statistics obtained by transmission electron microscopy, which showed that the densities of grain boundaries, dislocations and twin boundaries have all been lowered by annealing. The same set-up was then used to study the hydriding equilibrium and kinetic behaviour of the resulting films at room temperature. A full quantitative analysis of their hydriding cycles showed that the rate constants of both the adsorption-and absorption-limited kinetic regimes were strongly affected by microstructure. Defect engineering was thereby shown to increase the rate constants for hydrogen adsorption and absorption in Pd by a factor 40 and 30, respectively.

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Section: Introductionmentioning

confidence: 92%

Effect of structural defects on the hydriding kinetics of nanocrystalline Pd thin films

Delmelle

Amin-Ahmadi

Sinnaeve

et al. 2015

International Journal of Hydrogen Energy

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“…Belonoshko et al [24] derived the temperature-dependent diffusivity of a-Al 2 O 3 (grain interior) and amorphous (grain boundary) alumina are (21.7 Â 10 À8 m 2 /s)exp(À1.24 ev/kT) and (8.71 Â 10 À7 m 2 /s)exp(À0.91 ev/kT), which indicated that the diffusion of tritium in grain boundary needed lower activation energy. With further crystallization and grain growth after 700 C-annealing of as-deposited coatings, the grain boundary fraction would increase drastically [25]. A great deal of deuterium molecules, which permeate 600 C-annealing coatings along defect, have to overcome high activation energy to diffuse through grain interior, which result in higher ability to impede deuterium permeation, i.e.…”

Section: Discussionmentioning

confidence: 98%

Study on influence factors of permeation reduction factor of Al 2 O 3 -hydrogen isotopes permeation barriers

Wang

Xiang

et al. 2016

International Journal of Hydrogen Energy

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“…17 Nonlinear least-squares fitting of Eq. 1 was used to determine the film stress r, where w is limited to sin 2 w = 0.08 with the bulk Ag cubic lattice constant a = 0.40853 nm for the unstressed bulk spacing d 0 333 = 0.0786 nm.…”

Section: Methodsmentioning

confidence: 99%

“…These XRD results were also used to calculate the residual stress of the sputtered Ag film at room temperature, using the sin 2 w method. 17 Five specimens were measured to determine the residual stress for each bonding condition. The diffraction peak at 2h = 156.87°was selected for this stress measurement, generated by monochromatic Cu K a1 radiation at 40 kV and 30 mA.…”

Section: Methodsmentioning

confidence: 99%

Pressureless Bonding Using Sputtered Ag Thin Films

Nagao

Suganuma

2014

Journal of Elec Materi

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To improve the performance and reliability of power electronic devices, particularly those built around next-generation wide-bandgap semiconductors such as SiC and GaN, the bonding method used for packaging must change from soldering to solderless technology. Because traditional solders are problematic in the harsh operating conditions expected for emerging hightemperature power devices, we propose a new bonding method in this paper, namely a pressureless, low-temperature bonding process in air, using abnormal grain growth on sputtered Ag thin films to realize extremely high temperature resistance. To investigate the mechanisms of this bonding process, we characterized the microstructural changes in the Ag films over various bonding temperatures and times. We measured the bonding properties of the specimens by a die-shear strength test, as well as by x-ray diffraction measurements of the residual stress in the Ag films to show how the microstructural developments were essential to the bonding technology. Sound bonds with high die strength can be achieved only with abnormal grain growth at optimum bonding temperature and time. Pressureless bonding allows for production of reliable high-temperature power devices for a wide variety of industrial, energy, and environmental applications.

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Size effect of thermal expansion and thermal/intrinsic stresses in nanostructured thin films: Experiment and model

Cited by 85 publications

References 22 publications

Effect of structural defects on the hydriding kinetics of nanocrystalline Pd thin films

Effect of structural defects on the hydriding kinetics of nanocrystalline Pd thin films

Study on influence factors of permeation reduction factor of Al 2 O 3 -hydrogen isotopes permeation barriers

Pressureless Bonding Using Sputtered Ag Thin Films

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