Demixing processes in AgPd superlattices

Dumont, Jacques; Sporken, R.; Verstraete, Matthieu J.; Ghijsen, J.; Gonze, Xavier

doi:10.1088/0953-8984/21/31/315002

Cited by 5 publications

(3 citation statements)

References 46 publications

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“…However, a new peak appears at 0.038 V vs. Ag/Ag + that might be caused by Ag upd on thinner terraces. STM measurements by Dumont et al show Ag deposition on Pd(111) starts at step edges [19]; thus, the first peak may also be due to Ag deposition at steps, which are more common on deposited films than on single crystals. The peak at 0.011 V vs. Ag/Ag + for Pd(111) is missing in CVs on the Pd film.…”

Section: Resultsmentioning

confidence: 99%

Hydrogen Evolution Electrocatalysis on AgPd(111) Alloys

Pluntke

Kibler

2011

Electrocatal

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Recent studies on AuPd(111) alloy surfaces display unexpected hydrogen evolution reaction activities-a unique activity of AuPd alloys with surface fractions of~20% Pd was found. We investigated if this phenomenon also occurs with AgPd alloys. We first deposited Pd on a Ru (0001) substrate. After annealing, cyclic voltammetry investigations showed the same characteristics as Pd (111) single crystals. During Ag deposition, cyclic voltammetry experiments disclose underpotential deposition of Ag on the Pd film just as on Pd(111). AgPd alloys were formed by further annealing, and strong enrichment of Ag at the surface is observed. Using this approach, we prepared various bulk compositions at a film thickness of 20 monolayers. Most AgPd alloys show a higher electrocatalytic activity than Ag or Pd alone. The activity trends match those seen with AuPd alloys.

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Section: Resultsmentioning

confidence: 99%

Hydrogen Evolution Electrocatalysis on AgPd(111) Alloys

Pluntke

Kibler

2011

Electrocatal

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“…[40][41][42] All of the new monoclinic peaks are shifted to higher 2 than the values for the m-HfO 2 standard. Kinetic demixing results in the formation of nonequilbrium structures that have a different chemistry from the mixed phase.…”

Section: Crystallization After Annealing At 1273 K "Stages VI and mentioning

confidence: 80%

Crystallization, metastable phases, and demixing in a hafnia-titania nanolaminate annealed at high temperature

Cisneros-Morales

Aita

2010

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Nanolaminate films with a nominal 5 nm HfO2–4 nm TiO2 bilayer architecture are sputter deposited on unheated fused silica and Au-coated glass substrates. Films on fused silica are postdeposition annealed from 573 to 1273 K and characterized by x-ray diffraction, scanning electron microscopy, Raman microscopy, and UV-visible-near IR spectrophotometry. The films show weak but progressive crystallization into orthorhombic (o) HfTiO4 when annealed up to 973 K. o-HfTiO4 is expected to form under bulk thermodynamic equilibrium conditions in the case of complete mixing of the bilayer components. Annealing above 973 K produces a crystallization sequence that is not predicted by bulk thermodynamics, ultimately involving o-HfTiO4 demixing to form monoclinic HfO2 doped with Ti and rutile TiO2 doped with Hf. These phases have a higher atomic density than o-HfTiO4 and segregate into discrete mesoscopic features. The authors propose that o-HfTiO4 demixing into higher density phases is a mechanism for thermal stress relief at high temperature. Demixing results in a major loss of optical transparency in the visible and ultraviolet spectral regions.

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“…New ordered phases may appear as a result of minimization of surface and interface strains and energy. Therefore, alloying between immiscible elements is allowed [ 25 ]. Pd-Ir constitutes face-centered cubic alloys with a reduced lattice constant compared to pure metals.…”

Section: Introductionmentioning

confidence: 99%

The Effect of the Iridium Alloying and Hydrogen Sorption on the Physicochemical and Electrochemical Properties of Palladium

2023

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Thin layers (up to 1 µm) of Pd-Ir alloys were electrodeposited from aqueous, galvanic baths of PdCl2 and IrCl3 mixtures. The morphology of the electrodeposits was examined by means of scanning electron microscopy. The composition of alloys was determined with the use of energy-dispersive spectroscopy, atomic absorption spectrometry, X-ray photoelectron spectroscopy, and Auger electron spectroscopy. For the studies of the electrochemical properties of alloys, cyclic voltammetry, chronoamperometry, and chronopotentiometry were used. It was found that Pd-Ir alloy electrodes were surface-enriched with Pd. Pd-Ir alloys subjected to different electrochemical treatment involving hydrogen sorption changed their surface state. The continuous hydrogen sorption enhanced the Ir ions’ dissolution. The values of thermodynamic functions of hydrogen sorption in strong alkaline electrolytes were comparable with those in acidic electrolytes, whereas the kinetics of the process in alkaline medium was hindered. The miscibility gap in the Pd-Ir-H system vanished for the electrode containing ca. 93.7 at.% Pd.

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Demixing processes in AgPd superlattices

Cited by 5 publications

References 46 publications

Hydrogen Evolution Electrocatalysis on AgPd(111) Alloys

Hydrogen Evolution Electrocatalysis on AgPd(111) Alloys

Crystallization, metastable phases, and demixing in a hafnia-titania nanolaminate annealed at high temperature

The Effect of the Iridium Alloying and Hydrogen Sorption on the Physicochemical and Electrochemical Properties of Palladium

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