Pd-Ag Electrical Resistivity in Hydrogen and Deuterium: Temperature Effect
Alfonso Pozio1, Silvano Tosti2
1Department of Energy Technologies, ENEA C.R. Casaccia, Via Anguillarese 301, S. Maria di Galeria, 00123 Rome, Italy. alfonso.pozio@enea.it.
Materials (Basel, Switzerland)
|November 2, 2019
Summary
The electrical resistivity of palladium-silver (Pd-Ag) alloys differs between hydrogen and deuterium atmospheres due to isotope ratios and lattice positions. This study explores these differences in Pd-Ag for hydrogen technologies.
Area of Science:
- Materials Science
- Physical Chemistry
- Solid State Physics
Background:
- Palladium alloys are crucial for hydrogen storage and separation.
- Understanding hydrogen and deuterium interactions with metals is vital for technological applications.
- Electrical resistivity is a sensitive probe of material properties and phase transitions.
Purpose of the Study:
- To investigate the electrical resistivity of Pd-Ag (21 wt.% Ag) alloys in hydrogen and deuterium atmospheres.
- To analyze the influence of different isotopes on the alloy's electrical properties.
- To elucidate the relationship between isotope behavior, lattice interactions, and resistivity changes.
Main Methods:
- Electrochemical impedance spectroscopy was employed to measure electrical resistivity.
- Experiments were conducted in hydrogen and deuterium atmospheres at 100 kPa.
- Temperature ramping (25-250 °C) was used to observe resistivity changes.
Main Results:
- Pd-Ag exhibited characteristic S-shaped resistivity curves versus temperature, with distinct minima and maxima for hydrogen and deuterium.
- Isotope ratios (H/M, D/M) and their lattice positions significantly influenced resistivity.
- A hysteresis effect was observed during temperature ramping in hydrogen, attributed to differing isotope energy levels in O-sites and T-sites.
Conclusions:
- The electrical resistivity of Pd-Ag alloys is sensitive to the presence and behavior of hydrogen and deuterium isotopes.
- Differences in isotope ratios and their occupation of interstitial sites (O-sites, T-sites) lead to distinct resistivity responses.
- These findings provide insights into the fundamental interactions of hydrogen isotopes within palladium-based alloys, relevant for materials design in hydrogen technologies.
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