Amorphous Structures in the Immiscible Ag-Ni System

He, Jianyu; Sheng, H. W.; Schilling, Paul J.; Chien, C. L.; Ma, E.

doi:10.1103/physrevlett.86.2826

Cited by 107 publications

(67 citation statements)

References 26 publications

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“…5 the non-zero chemical short-range order leads to ''spinodal-like'' structures in the Mg y Ti 1Ày alloys. Experimental evidence of such ''spinodal-like'' structures, characterized by compositional modulations with nanometer wavelengths [22], with similar values for the chemical shortrange order parameters, has been reported both for amorphous [24] and crystalline [25] immiscible binary systems. The pictures in Fig.…”

Section: Discussionmentioning

confidence: 99%

Nanoscale composition modulations in MgyTi1−yHx thin film alloys for hydrogen storage

Baldi

Gremaud

Borsa

et al. 2009

International Journal of Hydrogen Energy

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IntroductionThe Mg-Ti-H system is currently attracting a lot of attention, with potential applications in very different fields. Niessen et al. [1] proposed the use of Mg-Ti thin films as high-capacity hydrogen storage materials for batteries. By means of electrochemical loading of Mg 0.8 Ti 0.2 thin films they found a gravimetrical storage capacity of 6.53 wt% H: w4 times higher than the commercially available NiMH batteries. In our group we demonstrated the possibility of gas loading of Pdcapped Mg y Ti 1Ày thin films. These films, when exposed to hydrogen gas exhibit fast and reversible transitions from the metallic to the hydrogenated state. The Ti doping of Mg greatly enhances the kinetics of hydrogen uptake and release. A 65 nm thick film of Mg 0.7 Ti 0.3 , exposed to 5% H 2 in Ar at room temperature, hydrogenates completely in w10 s; if it is then exposed to 20% O 2 in Ar, it fully desorbs in less than 3 min, returning to its original metallic state [2]. The role of Ti is to favor the formation of a face-centered cubic hydride phase of Mg y Ti 1Ày H x (for y < 0.87 [3]) instead of the tetragonal MgH 2 -like phase.The hydrogenation of Mg y Ti 1Ày thin films is also accompanied by dramatic optical changes, which make them suitable for application as hydrogen sensors [4] and smart coating for solar collectors [5]: when exposed to hydrogen gas, they exhibit fast and reversible (>100 cycles) optical transitions

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Section: Discussionmentioning

confidence: 99%

Nanoscale composition modulations in MgyTi1−yHx thin film alloys for hydrogen storage

Baldi

Gremaud

Borsa

et al. 2009

International Journal of Hydrogen Energy

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show abstract

“…However, some degree of energy minimization results in the development of local structures on extremely fine scales. 4 Formation and stabilization of amorphous phases in immiscible systems have also been reported, 5,6 along with a strong clustering tendency leading to non-uniform spinodal-like structures. 5 Vapor deposition and other far-from-equilibrium processing techniques may be employed to extend solid solubility in immiscible systems.…”

Section: Introductionmentioning

confidence: 99%

“…4 Formation and stabilization of amorphous phases in immiscible systems have also been reported, 5,6 along with a strong clustering tendency leading to non-uniform spinodal-like structures. 5 Vapor deposition and other far-from-equilibrium processing techniques may be employed to extend solid solubility in immiscible systems. [5][6][7][8][9][10][11][12][13] Sputtering represents a versatile technique for producing homogeneous thin films of immiscible alloys with varying composition and tunable properties.…”

Section: Introductionmentioning

confidence: 99%

“…5 Vapor deposition and other far-from-equilibrium processing techniques may be employed to extend solid solubility in immiscible systems. [5][6][7][8][9][10][11][12][13] Sputtering represents a versatile technique for producing homogeneous thin films of immiscible alloys with varying composition and tunable properties. 14,15 While there are a few studies on the structure as a function of composition for silver-copper alloys by far-from-equilibrium processing, 13,[16][17][18] there are no reports on the physics of electrical transport in this immiscible system of immense technological importance.…”

Section: Introductionmentioning

confidence: 99%

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Metallic Glass Nano-composite Thin Films for High-performance Functional Applications

Das

Arora

Mukherjee

2017

JOM

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Metallic glass nanocomposite thin films were synthesized for an immiscible Ag-Cu alloy system by magnetron sputtering. The structure of the films was unique, consisting of homogeneously dispersed nanocrystallites in an amorphous matrix. The size and volume fraction of the nanocrystallites increased with increasing film thickness resulting in increased elastic modulus and hardness. The high electrical conductivity of the nanocomposite films was examined by a valence-band study, which showed that exchange interaction between Ag and Cu in the nanocomposite structure resulted in enhanced charge carrier concentration. The inverse correlation between electrical conductivity and film thickness was explained by surface and interface scattering of electrons with increasing volume fraction of nanocrystallites. The small temperature dependence of conductivity was attributed to the distorted Fermi surface of the nanocomposite films resulting in a greater contribution from structure scattering, which is temperature-independent.

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“…For the case of immiscible binary metal alloys (e.g., Ag-Cu) the latter metastable structure is typically found to be an inhomogeneous crystalline solid solution, in the sense that preferential clustering of the single elements occurs on the nanometer length scale [100]. In addition to the solid solution-like structure, amorphous ** alloys can ** Amorphous refers to lack of long range order, but short range ordering or clustering has been shown [101]. also form by further lowering the degree of diffusivity [100,102].…”

Section: Miscible and Immiscible Systemsmentioning

confidence: 99%

Nanoscale structure forming processes : Metal thin films grown far-from-equilibrium

Elofsson¹

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The cover image shows a high angle annular dark field scanning transmission electron microscopy micrograph of elongated Ag-Cu atomic islands supported on a SiO 2 substrate. Intensity variation within each island stems from mass contrast caused by segregation into Ag-and Cu-rich domains. Image courtesy of Dr. Robert D. Boyd.During the course of research underlying this thesis, Viktor Elofsson was enrolled in Agora Materiae, a multidisciplinary doctoral program at Linköping University, Sweden.© Viktor Elofsson, unless otherwise stated. Printed by LiU-Tryck, Linköping, 2016. Till mormor. AbstractThin film growth from the vapor phase has for a long time intrigued researchers endeavouring to unravel and understand atomistic surface processes that govern film formation. Their motivation has not been purely scientific, but also driven by numerous applications where this understanding is paramount to knowledge-based design of novel film materials with tailored properties.Within the above framework, this thesis investigates growth of metal films on weakly bonding substrates, a combination of great relevance for applications concerning e.g., catalysis, graphene metallization and architectural glazing. When metal vapor condenses on weakly bonding substrates three dimensional islands nucleate, grow and coalesce prior to forming a continuous film. The combined effect of these initial growth stages on film formation and morphology evolution is studied using pulsed vapor fluxes for the model system Ag/SiO 2 . It is shown that the competition between island growth and coalescence completion determines structure evolution. The effect of the initial growth stages on film formation is also examined for the tilted columnar microstructure obtained when vapor arrives at an angle that deviates from the substrate surface normal. This is done using two metals with distinctly different nucleation behaviour, and the findings suggest that the column tilt angle is set by nucleation conditions in conjunction with shadowing of the vapor flux by adjacent islands. Vapor arriving at an angle can in addition result in films that exhibit preferred crystallographic orientations, both out-of-plane and in-plane. Their emergence is commonly described by an evolutionary growth model, which for some materials predict a double in-plane alignment that has not been observed experimentally. Here, an experiment is designed to replicate the model's growth conditions, confirming the existence of double in-plane alignment.New and added film functionalities can further be unlocked by alloying. Properties are then largely set by chemistry and atomic arrangement, where the latter can be affected by thermodynamics, kinetics and vapor flux modulation. Their combined effect on atomic arrangement is here unravelled by presenting a research methodology that encompasses high resolution vapor flux modulation, nanoscale structure v vi probes and growth simulations. The methodology is deployed to study the immiscible Ag-Cu and miscible Ag-Au model systems, for which it...

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Amorphous Structures in the Immiscible Ag-Ni System

Cited by 107 publications

References 26 publications

Nanoscale composition modulations in MgyTi1−yHx thin film alloys for hydrogen storage

Nanoscale composition modulations in MgyTi1−yHx thin film alloys for hydrogen storage

Metallic Glass Nano-composite Thin Films for High-performance Functional Applications

Nanoscale structure forming processes : Metal thin films grown far-from-equilibrium

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