Composition control of Pd-Cu-Si metallic glassy alloys for thin film hydrogen sensor

Abstract

Pd-Cu-Si metallic glassy alloys were investigated as materials for a hydrogen sensor. We prepared thin films of Pd-Cu-Si metallic glassy alloys with varying compositions by RF magnetron sputtering method. And effects of their composition on thermal properties (Tg: glass transition temperature, Tx: crystallization temperature) and H2 response were examined. The H2 response was examined by measuring changes of electric resistance of the thin films exposed in N2 and H2. Thermal stability depending on thermal properties and large response to hydrogen are key requirements of the hydrogen sensor. Tg and Tx and H2 response were significantly affected by Si content. Tg and Tx became higher and H2 response decreased when Si content was increased. As for metals, Pd and Cu, Tg increased and H2 response decreased with decreasing Pd/Cu atomic ratio among the samples having almost the same Si contents. These results can be explained by a trigonal prism cluster that is reported as a structural unit of Pd-based amorphous alloy. We discussed the effects of a trigonal prism cluster on thermal properties and H2 response, as well as the effects of Si content and Cu content on constructing trigonal prism clusters. © 2010 The Japan Institute of Metals.