Adhesion energy between metal films and polymers obtained by studying buckling induced by hydrogen

Pundt, Astrid; Nikitin, E. V.; Pekarski, Pavel; Kirchheim, R.

doi:10.1016/j.actamat.2003.12.003

Cited by 85 publications

(50 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In particular, in buckled thin films there is much less in-plane additional strain energy involved during hydrogen absorption than in films fully clamped on the substrate. 17 The strain reduction induced by buckling and cracking is most probably responsible for the observed shrinkage of the hysteresis loop between cycles 1 and 18. In Fig.…”

Section: Fig 3 ͑Color Online͒ ͑Symbols͒mentioning

confidence: 99%

An optical method to determine the thermodynamics of hydrogen absorption and desorption in metals

Gremaud

Slaman

Schreuders

et al. 2007

Applied Physics Letters

View full text Add to dashboard Cite

Hydrogenography, an optical high-throughput combinatorial technique to find hydrogen storage materials, has so far been applied only to materials undergoing a metal-to-semiconductor transition during hydrogenation. We show here that this technique works equally well for metallic hydrides. Additionally, we find that the thermodynamic data obtained optically on thin Pd-H films agree very well with Pd-H bulk data. This confirms that hydrogenography is a valuable general method to determine the relevant parameters for hydrogen storage in metal hydrides. © 2007 American Institute of Physics. ͓DOI: 10.1063/1.2821376͔ Energy storage, and particularly storage of hydrogen as an energy carrier, is a major issue for the possible implementation of a "hydrogen economy." 1 Metal hydrides provide an attractive option to store hydrogen reversibly. The standard approach for the search of hydrogen storage materials is to synthesize bulk samples and to use volumetric, gravimetric or calorimetric techniques to follow the hydrogen evolution in the sample. The great disadvantage of this approach is that a bulk sample is needed for each investigated chemical composition. Thin films provide an interesting alternative to bulk, as heat and hydrogen diffusion issues are minimized by the thin film geometry. When thin film metal alloys are deposited in a combinatorial way, the surface science and optical techniques allow for a fast screening of the hydrogen absorbing compositions. 2 Recently we have determined the enthalpy and entropy of hydrogen absorption of thousands of different Mg-Ni-Ti compositions simultaneously by hydrogenography, our optical combinatorial technique. 3 While the asdeposited alloys are metallic, the different Mg, Mg-Ni, and Mg-Ti hydrides formed upon hydrogenation are all heavily doped semiconductors. This results in the opening of an optical bandgap. The large optical contrast in transmission in the visible range between the metals and the semiconductor hydrides facilitates the optical measurements. However, as some potential hydrogen storage materials may not undergo a metal-to-semiconductor transition, it is important to demonstrate the applicability of hydrogenography to metallic hydrides. For this we choose the archetypal Pd-H system that has been extensively studied in bulk, 4-6 cluster, 7,8 or thin film form. 9,10 The pressure-concentration isotherms ͑PCI͒ of Pd-H exhibit wide plateaus where the low hydrogen ␣-PdH x phase coexists with the nonstoichiometric ␤-PdH x hydride phase. The 3.54% lattice mismatch 11 ͑11% in volume͒ between the ␣ and the ␤ phases results in an expansion upon hydrogenation that generates large stresses and plastic deformation. This means that, upon cycling, the macroscopic Pd decrepitates into grains of a few micrometer size. While very thin films ͑thickness ഛ10 nm͒ remain clamped to the substrate, 12 in thicker films most of the hydrogen compressive stress is released by the production of networks of large buckles ͑30-50 times the film thickness͒. 13 In this letter, we present a metho...

show abstract

Section: Fig 3 ͑Color Online͒ ͑Symbols͒mentioning

confidence: 99%

An optical method to determine the thermodynamics of hydrogen absorption and desorption in metals

Gremaud

Slaman

Schreuders

et al. 2007

Applied Physics Letters

View full text Add to dashboard Cite

show abstract

“…Hence, there is a high probability for positron trapping in open volume defects at interfaces between columns. Since a straight buckle can release the in-plane stress only in a single in-plane direction the film is forced to expand also in the perpendicular direction [2]. As a consequence in the further stage of buckling (0.15 < x H < 0.20) the buckles become curved, see Fig.…”

Section: Resultsmentioning

confidence: 99%

“…plastic deformation) one can expect that new defects are introduced during buckling process. Although the morphology of buckles was investigated in a number of works [2][3][4], there is still a lack of information about defect evolution in buckled films. In the present work slow positron implantation spectroscopy (SPIS) was employed for characterization of development of defects in thin Pd films loaded with hydrogen.…”

mentioning

confidence: 99%

“…As a consequence, high compressive bi-axial in-plane stresses up to several GPa occur in thin films loaded with hydrogen [1]. These hydrogen-induced stresses grow with increasing hydrogen content and may cause local or global detachment of the loaded film from the surface, which results in formation of buckles with various morphologies [2][3][4]. Understanding of hydrogen-induced buckling is highly important since this process may cause catastrophic adhesion failure in many thin film systems or coatings exposed to hydrogen.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Structural Studies of Nanocrystalline Thin Pd Films Electrochemically Doped with Hydrogen

Čı́žek

Vlček

Lukáč

et al. 2012

DDF

View full text Add to dashboard Cite

Abstract. Hydrogen absorption in Pd causes a significant volume expansion. In free-standing bulk Pd, the hydrogen-induced volume expansion is isotropic. However, the situation becomes more complicated in thin Pd films. Contrary to bulk samples, thin films are clamped to an elastically stiff substrate, which prevents in-plane expansion. Hence, the volume expansion of a thin film is strongly anisotropic because it expands in the out-of-plane direction only. Internal stresses introduced by absorbed hydrogen may become so high that detachment of a film from the substrate is energetically favorable and buckles of various morphologies are formed. In the present work, we studied hydrogen-induced buckling in a nanocrystalline thin Pd film deposited on a sapphire substrate. Slow positron implantation spectroscopy (SPIS) was employed as a principal tool for the characterization of defects and investigation of defect interactions with hydrogen. SPIS studies were combined with X-ray diffraction and direct observations of buckling by light microscopy. It was found that buckling of thin Pd film occurs at hydrogen concentrations x H > 0.1 and is accompanied by a strong increase of dislocation density. IntroductionHydrogen dissolved in interstitial sites in a host metal lattice causes a volume expansion, which is isotropic in free standing bulk samples. However, in thin films, in-plane expansion is hindered by clamping of the film to the substrate. This makes hydrogen-induced expansion strongly anisotropic: the in-plane expansion is suppressed, while the out-of-plane expansion is remarkably larger than in a free standing bulk metal. As a consequence, high compressive bi-axial in-plane stresses up to several GPa occur in thin films loaded with hydrogen [1]. These hydrogen-induced stresses grow with increasing hydrogen content and may cause local or global detachment of the loaded film from the surface, which results in formation of buckles with various morphologies [2][3][4]. Understanding of hydrogen-induced buckling is highly important since this process may cause catastrophic adhesion failure in many thin film systems or coatings exposed to hydrogen.Hydrogen-induced buckling occurs when the stored elastic strain energy overcomes the adhesion energy to the surface. Since the formation of buckles represents an irreversible change of film shape (i.e. plastic deformation) one can expect that new defects are introduced during buckling process. Although the morphology of buckles was investigated in a number of works [2][3][4], there is still a lack of information about defect evolution in buckled films. In the present work slow positron implantation spectroscopy (SPIS) was employed for characterization of development of defects in thin Pd films loaded with hydrogen. Defect studies by SPIS were combined with X-ray diffraction (XRD) and direct observations of buckles by light microscopy.

show abstract

“…Neither buckling, nor detachment of the film from the substrate, was observed after hydrogen loading, indicating good adhesion between the Ti-films and the sapphire substrates. The stresses developing in the film during hydrogen loading were in situ determined by measuring the deflection of the substrate using the setup described elsewhere [13], calculating its radius of curvature and inserting it to Stoney's equation [14]:…”

Section: Methodsmentioning

confidence: 99%

The influence of films thickness on hydrogenation behavior of titanium thin films

Tal-Gutelmacher¹,

Pundt²,

Kirchheim³

2010

J Mater Sci

View full text Add to dashboard Cite

Titanium films of different thicknesses were prepared on sapphire substrates in an UHV chamber, by means of ion beam sputter deposition at room temperature, under Ar-atmosphere at the pressure of 1.5Á10 E -4 mbar. For electrochemical hydrogen loading, the films were covered by a 30-nm thick layer of Pd in order to prevent oxidation and facilitate hydrogen absorption. In situ stress measurements were conducted during step-by-step electrochemical hydrogen charging of the films. XRD measurements using a Phillips X-Pert diffractometer with a Co-Ka radiation were performed before and after hydrogenation in order to investigate the effect of hydrogen loading on the microstructure. The phase boundaries, as well as the stress and strain development during hydrogen absorption, depend strongly on the thickness of the films. The main characteristics of absorption behavior of hydrogen, as well as the thermodynamics and phase boundaries of titanium-hydrogen thin films are discussed in detail with specific emphasis on the influence of films thickness. The obtained results are also compared to literature data on the widely studied titanium-hydrogen bulk system. Shifted phase boundaries and narrowed two-phase field appear in Ti-H film system, which are mainly attributed to the microstructural contribution, as well as to the large stresses in the GPa-range that built up between the films and their substrate.

show abstract

Adhesion energy between metal films and polymers obtained by studying buckling induced by hydrogen

Cited by 85 publications

References 17 publications

An optical method to determine the thermodynamics of hydrogen absorption and desorption in metals

An optical method to determine the thermodynamics of hydrogen absorption and desorption in metals

Structural Studies of Nanocrystalline Thin Pd Films Electrochemically Doped with Hydrogen

The influence of films thickness on hydrogenation behavior of titanium thin films

Contact Info

Product

Resources

About