In situ neutron-reflectometry measurements of hydrogen and deuterium absorption in a Pd/Nb/Pd layered film

Munter, Alan E.; Heuser, Brent J.; Ruckman, M. W.

doi:10.1103/physrevb.55.14035

Cited by 10 publications

(6 citation statements)

References 12 publications

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“…In contrast, the scattering length for neutrons varies randomly from element to element, and, as a consequence, hydrogen in a given material usually scatters as strongly, or sometimes stronger, than the absorbing medium. The fact that both hydrogen and deuterium atoms strongly scatter neutrons opens up the opportunity for isotope contrast variation [39]. These combined properties make neutron scattering a unique tool to identify the location and concentration of hydrogen in hydride materials.…”

Section: Introduction: Hydrogen Absorption In Metals-bulk Versus Thinmentioning

confidence: 99%

Hydrogen Absorption in Metal Thin Films and Heterostructures Investigated in Situ with Neutron and X-ray Scattering

Callori

Rehm

Causer

et al. 2016

Metals

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Due to hydrogen possessing a relatively large neutron scattering length, hydrogen absorption and desorption behaviors in metal thin films can straightforwardly be investigated by neutron reflectometry. However, to further elucidate the chemical structure of the hydrogen absorbing materials, complementary techniques such as high resolution X-ray reflectometry and diffraction remain important too. Examples of work on such systems include Nb-and Pd-based multilayers, where Nb and Pd both have strong affinity to hydrogen. W/Nb and Fe/Nb multilayers were measured in situ with unpolarized and polarized neutron reflectometry under hydrogen gas charging conditions. The gas-pressure/hydrogen-concentration dependence, the hydrogen-induced macroscopic film swelling as well as the increase in crystal lattice plane distances of the films were determined. Ferromagnetic-Co/Pd multilayers were studied with polarized neutron reflectometry and in situ ferromagnetic resonance measurements to understand the effect of hydrogen absorption on the magnetic properties of the system. This electronic effect enables a novel approach for hydrogen sensing using a magnetic readout scheme.

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Section: Introduction: Hydrogen Absorption In Metals-bulk Versus Thinmentioning

confidence: 99%

Hydrogen Absorption in Metal Thin Films and Heterostructures Investigated in Situ with Neutron and X-ray Scattering

Callori

Rehm

Causer

et al. 2016

Metals

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“…Later, Munter et al showed how deuterium absorption could be monitored in-situ during loading experiments on thin Pd films 9,10 . More recently, a series of studies has been published by Fritzche et al, showing how NR can be used to investigate the thermodynamics of hydrogen uptake process in Pd-capped metal alloy films [11][12][13][14][15] .…”

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confidence: 99%

Surface oxide on thin films of yttrium hydride studied by neutron reflectometry

Mongstad

Platzer‐Björkman

Mæhlen

et al. 2012

Applied Physics Letters

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The applicability of standard methods for compositional analysis is limited for H-containing films. Neutron reflectometry is a powerful, non-destructive method that is especially suitable for these systems due to the large negative scattering length of H. In this work we demonstrate how neutron reflectometry can be used to investigate thin films of yttrium hydride. Neutron reflectometry gives a strong contrast between the film and the surface oxide layer, enabling us to estimate the oxide thickness and oxygen penetration depths. A surface oxide layer of 5-10 nm thickness was found for unprotected yttrium hydride films.

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“…[19][20][21][22][23][24][25][26][27][28][29][30] This ability is empowered by the high contrast between hydrogen isotopes (hydrogen and deuterium) which can be used to precisely probe, non-destructively, the amount of hydrogen penetrating into the metal and any surface films. The fact that NR can be carried out in situ by applying a controlled electrochemical condition adds a new dimension to the study of hydrogen transport through the oxide and metal films, and of their corrosion resistance.…”

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confidence: 99%

Hydrogen Absorption into Titanium under Cathodic Polarization: An In-Situ Neutron Reflectometry and EIS Study

Vezvaie¹,

Noël

Tun³

et al. 2013

J. Electrochem. Soc.

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Hydrogen (deuterium) absorption into sputter-coated titanium (Ti) film electrodes during cathodic polarization in heavy water (D 2 O) was monitored using in-situ neutron reflectometry (NR) and electrochemical impedance spectroscopy (EIS). The scattering length density (SLD) of Ti metal increased with increasing cathodic polarization, due to the penetration of deuterium through the surface oxide and into the underlying metal. The rate of D absorption estimated from the NR data showed a pattern with four distinctive regions separated by potential boundaries between −0.35 and −0.4 V SCE and around ∼−0.6 V SCE . EIS results support division of the behavior into these potential ranges. Hydrogen absorption by Ti was observed at potentials <∼−0.35 V SCE , where the capacitance and resistance of the TiO 2 layer dramatically changed. At this point, the D content of the film quickly achieved a level of ∼900 ppm by weight (atom ratio D:Ti ∼ 0.04). Decreased absorption kinetics were observed over the potential region from ∼−0.40 V SCE to −0.6 V SCE , indicating that D absorption was controlled either by a diffusion process through the TiO 2 layer or by the formation of blocking hydrides at the Ti/TiO 2 interface, at the base of the defective locations in the oxide through which the hydrogen was entering. Significant increases in the current density and SLD of the Ti film at potentials more negative than −0.6 V SCE were assigned to widespread hydrogen absorption and TiH x growth within the metal. These observations are consistent with hydrogen ingress through the oxide film, probably via weak points containing electronic defects and disorder, such as grain boundaries and triple points, at potentials as mild as ∼−0.4 V SCE , and with hydrogen penetration through continuous, intact oxide via the previously published redox transformation mechanism, at potentials more negative than −0.6 V SCE . Titanium corrosion processes are often accompanied by hydrogen production. For example, 80% or more of the crevice corrosion process on Ti is driven by the reduction of protons inside the crevice:This leads to the absorption of atomic hydrogen, and can result in extensive hydride formation. 1,2 Cathodic polarization and galvanic coupling with active metals can also cause hydrogen evolution on the Ti surface and hydrogen penetration into the bulk metal. Since hydrogen absorption into Ti structures can lead to their failure by brittle cracking, once the hydrogen concentration achieves a critical level, 3 safe operation of such structures requires a detailed knowledge of the mechanism of hydrogen entry into Ti so that exposure conditions that put the structure at risk of hydrogen-induced cracking can be avoided. A number of studies have been done on the physicochemical properties of Ti/H systems, as well as on hydrogen-induced cracking of Ti.3,4 Here we explore the role of the electrochemical potential in determining whether adsorbed hydrogen atoms generated by water reduction can penetrate the native oxide on Ti.The surface oxide layer play...

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In situ neutron-reflectometry measurements of hydrogen and deuterium absorption in a Pd/Nb/Pd layered film

Cited by 10 publications

References 12 publications

Hydrogen Absorption in Metal Thin Films and Heterostructures Investigated in Situ with Neutron and X-ray Scattering

Hydrogen Absorption in Metal Thin Films and Heterostructures Investigated in Situ with Neutron and X-ray Scattering

Surface oxide on thin films of yttrium hydride studied by neutron reflectometry

Hydrogen Absorption into Titanium under Cathodic Polarization: An In-Situ Neutron Reflectometry and EIS Study

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