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Composition Dependence of Electrical Resistivity of Magnesium-cobalt Films During Hydridation and Dehydridation

Published online by Cambridge University Press:  01 February 2011

Yiu Bun Chan  and
Chung Wo Ong
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

Palladium (Pd)-coated magnesium-cobalt (Mg-Co) films were prepared by co-sputtering at various ratios of the sputtering power of Mg to that of Co (PMg/PCo). The elemental composition of the films varies coherently with PMg/PCo. Films of higher Mg contents are of stronger interest. Their structures are more disordered even when just a relatively small amount of Co is added. The respective elemental contents are not uniform along depth, but more Mg aggregate near the surface region. A substantial volume fraction of Mg oxide is present. Though of structural complications, a Mg-rich film shows stronger and faster resistivity (ρ) response when reacting with hydrogen. Soaking an as-deposited Mg-rich film in 15% H2 (in argon) gives a huge change of ρ by 40 times, but it is mainly due to some irreversible structural change when a freshly prepared sample is first brought into contact with H2. The change of ρ in subsequent hydridation-dehydridation cycles is about 50%, while the drift of the baseline is less severe. Co-rich films give much weaker resistivity response to H2.

Keywords

hydrogenationMgsputtering
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1042: Symposium S – Materials and Technology for Hydrogen Storage , 2007 , 1042-S02-05
Copyright
Copyright © Materials Research Society 2008

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