Elastic Properties of Hydrogen-Loaded Epitaxial Films*, **

Reimer, P. M.; Zabel, H.; Flynn, C. P.; Matheny, A.; Ritley, K. A.; Steiger, J.; Blässer, S.; Weidinger, A.

doi:10.1524/zpch.1993.181.part_1_2.367

Cited by 25 publications

(20 citation statements)

References 21 publications

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“…For small hydrogen concentrations, the experimentally obtained expansion of 0.136 × c H is in good accordance with theoretical values obtained by using linear elastic theory [5]. An extraordinary large lattice expansion of 0.57 × c H has been reported by Reimer et al [12], but the origin for this behavior is still unclear. For large hydrogen concentrations, plastic deformation leads to a reduced out-of-plane lattice expansion [5,13].…”

Section: Introductionsupporting

confidence: 88%

Hydrogen-related surface modifications of 20nm thin straight-sided niobium nano-wires and niobium meander-films

Pundt

Nörthemann

Schmidt

2007

Journal of Alloys and Compounds

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Section: Introductionsupporting

confidence: 88%

Hydrogen-related surface modifications of 20nm thin straight-sided niobium nano-wires and niobium meander-films

Pundt

Nörthemann

Schmidt

2007

Journal of Alloys and Compounds

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“…Because of the transverse expansion this expansion is larger than bulk expansion. [27,28] Calculating stresses for hydrogen loaded films yield a compressive stress of ±12,6 GPa/(H/Pd) for Pd-H or ±9,8 GPa/(H/Nb) for Nb-H. [29] These predicted stresses are extraordinarily large. It is expected that the metal-hydrogen system properties are influenced by these large stresses.…”

Section: Substrate Influencementioning

confidence: 99%

Hydrogen in Nano‐sized Metals

Pundt¹

2004

Adv Eng Mater

148

101

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Nano-sized metal systems have received growing attention during the last decade which is not only motivated by the technological interest in low-dimensional systems providing the size reduction of electronic devices, but also by fundamental interest since physical properties tend to show interesting changes when the size of the system is reduced. So called finite-size effects become relevant as soon as the system-size is in the order of the correlation length of the system. Surface-as well as interface-effects influence strongly the system behaviour when their relative fraction compared to the volume increases. Furthermore, often substrate contributions influence the system properties. All these contributions become more relevant when the system size goes down to the nanometer-range. This range is, especially with regard to applications, a major field of interest: low-dimensional patterning of electronic devices still can increase the information density or might reduce the size of the product of interest. On the other hand, surface related processes, for example catalysts demand for nano-sized materials providing a large amount of active surface area. Physical properties of these systems, for example phase boundaries and lattice structures, tend to be quite different from those of the large size ªbulkº system. Therefore, the understanding of general rules or trends occurring at minimisation of metal-systems is an important problem that still needs to be solved.Nano-sized metal systems are mostly found in the shape of thin films, rods or clusters. Also stacking of nano-sized systems in so-called multi-layers causes interesting sample morphologies with a high density of interface volume (see Fig. 1).The physical properties of such nano-sized systems can be studied by choosing systems with a highly mobile alloying partner: the metal-hydrogen systems. The big advantage of such a system is that alloying is possible just by increasing the partial hydrogen-gas pressure (or chemical potential). According to Sieverts the concentration c H (given by the number of H-atoms per metal-atoms H/M) inside a metal is connected with the gas-pressure p H2 expressed by the solubility S 0 , c H =S 0 Öp H2 . [1] This equation holds for the low-concentration-range for all metals at the most up to the concentration where a hydride is formed. This concentration is called the solubility limit. The solubility S 0 varies significantly, for example for bulk Yttrium (Y) or Niobium (Nb) it is up to 10 11 or 10 3 , respectively, down to small values of 10 ±1 for bulk Palladium (Pd) or 10 ±20 for Tungsten (W). This implies huge differences in the hydrogen concentration for different metals at the same hydrogen gas pressure (chemical potential). However, the solubility for the nano-sized system can be different compared to bulk.Because of its small size and its ability to tunnel between neighbouring interstitial lattice sites, hydrogen is highly mobile. Diffusion constants such as 3´10 ±7 cm 2 /s for Pd (at 300 K) are usual, resulting in diffusio...

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“…In addition, an unusually large H-induced lattice expansion has been reported, 6 and the maximum out of plane lattice parameter change increases for thinner films. 3 No previous measurements have been done to address the role of the initial strain state of the Nb͑110͒-layers on the H-H-interaction.…”

Section: Introductionmentioning

confidence: 97%

H-H interactions in Nb/W(110) superlattices

et al. 2002

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The elastic interaction of hydrogen in Nb/W͑110͒ superlattices and the effect of biaxial compressive strain of the Nb layers on the hydrogen lattice-gas to hydrogen lattice-liquid (␣Ϫ␣Ј) phase boundary are explored. The epitaxial growth of Nb on W introduces biaxial compressive strain in the Nb layers and the degree of compression is governed by the thickness ratio of the constituents. Hydrogen solubility isotherms of four samples of increasing W-layer thickness (D W ϭ3 -18 ML) and a constant Nb-layer thickness ͑12 ML͒ were measured by combining resistivity measurements and the 1 H( 15 N,␣␥) 12 C nuclear reaction. ⌬H H and ⌬S H as functions of the hydrogen concentration and W-layer thickness were deduced. The H-H-interaction was found to depend strongly on the initial strain of the Nb host-lattice. The critical temperature for the ␣-␣Ј transition was determined to be 287 K for the sample with least compressed Nb layers (D W ϭ3), while no transition of this kind is verified for the other samples.

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Elastic Properties of Hydrogen-Loaded Epitaxial Films*, **

Cited by 25 publications

References 21 publications

Hydrogen-related surface modifications of 20nm thin straight-sided niobium nano-wires and niobium meander-films

Hydrogen-related surface modifications of 20nm thin straight-sided niobium nano-wires and niobium meander-films

Hydrogen in Nano‐sized Metals

H-H interactions in Nb/W(110) superlattices

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