Hydrogen retention in Pd-Ag (silver 21 wt. %) thin foil has been tested by means of temperature-programmed desorption (TPD) in the temperature range 25-200 ffiC and compared to the resistivity measurements for the purpose of explaining the characteristic S-shaped resistivity curve and its minimum observed in the same temperature range. The TPD results indicated that the highest uptake of hydrogen was between 65 ffiC and 105 ffiC, with a maximum at ~85 ffiC. Furthermore, in all examined cases, the hydrogen desorption peak was between 140 ffiC and 180 ffiC. The resistivity measurements in argon, hydrogen, and vacuum allowed us to examine the influence of hydrogen on the resistivity of a Pd-Ag alloy. The results showed evidence of two kinds of hydrides: (1) a weak absorption at low temperature (T < 70 ffiC) with the hydrogen present mainly in tetrahedral sites, and (2) a strong absorption up to 150 ffiC with the hydrogen present mainly in octahedral sites. The behaviour of the electrical resistivity and the minimum between 90 ffiC and 110 ffiC can be explained by the two kinds of hydrogen uploaded into the metal lattice.

Hydrogen absorption in Pd-Ag systems: A TPD and electrical resistivity study

Pozio A.;Tosti S.
2019

Abstract

Hydrogen retention in Pd-Ag (silver 21 wt. %) thin foil has been tested by means of temperature-programmed desorption (TPD) in the temperature range 25-200 ffiC and compared to the resistivity measurements for the purpose of explaining the characteristic S-shaped resistivity curve and its minimum observed in the same temperature range. The TPD results indicated that the highest uptake of hydrogen was between 65 ffiC and 105 ffiC, with a maximum at ~85 ffiC. Furthermore, in all examined cases, the hydrogen desorption peak was between 140 ffiC and 180 ffiC. The resistivity measurements in argon, hydrogen, and vacuum allowed us to examine the influence of hydrogen on the resistivity of a Pd-Ag alloy. The results showed evidence of two kinds of hydrides: (1) a weak absorption at low temperature (T < 70 ffiC) with the hydrogen present mainly in tetrahedral sites, and (2) a strong absorption up to 150 ffiC with the hydrogen present mainly in octahedral sites. The behaviour of the electrical resistivity and the minimum between 90 ffiC and 110 ffiC can be explained by the two kinds of hydrogen uploaded into the metal lattice.
Electrical resistivity; Hydrogen; Pd-Ag alloy; Temperature-programmed desorption
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/20.500.12079/51725
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