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Mechanisms for the Variation of Electrical Resistivity of Palladium Films in Hydridation-dehydridation Processes

Published online by Cambridge University Press:  01 February 2011

Yu Ming Tang
Affiliation:
[email protected], The Hong Kong Polytechnic University, Department of Applied Physics and Materials Research Center, Hung Hom, Kowloon, Hong Kong, N/A, China, People's Republic of
Yiu Bun Chan
Affiliation:
[email protected], The Hong Kong Polytechnic University, Department of Applied Physics and Materials Research Center, Hung Hom, Kowloon, Hong Kong, N/A, China, People's Republic of
Chung Wo Ong
Affiliation:
[email protected], The Hong Kong Polytechnic University, Department of Applied Physics and Materials Research Center, Hung Hom, Kowloon, Hong Kong, N/A, China, People's Republic of
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Abstract

Hydridation of palladium (Pd) is accompanied by a substantial volume expansion. The electrical resistivity (ρ) would rise because the volume fraction of the hydride phase increases. However, if the material structure is porous/defective, hydridation induced volume expansion may lead to the closing of some pores/defects to result in a drop of ρ. We verified that a magnetron sputtered Pd film deposited at a higher argon ambient pressure (ϕ) was more defective, such that the contribution from the latter mechanism was stronger with increasing ϕ, and reached a maximum level for a film deposited at a ϕ of 6 mTorr. However, the film structure was weaker and unstable during the switching cycles, such that the magnitude of the change of ρ was found to increase successively with increasing number of switching cycles. The performances of ρ during initial soaking in H2 and subsequent hydridation and dehydridation switching cycles were different. The observed results are presented and discussed in this paper.

Type
Research Article
Copyright
Copyright © Materials Research Society 2008

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