Dresden 2006 – scientific programme

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DS: Dünne Schichten

DS 24: Poster presentation

DS 24.21: Poster

Tuesday, March 28, 2006, 15:00–17:30, P2

Optical and electrical detection of hydrogen at room temperature based on MgNi switchable mirrors — •Baker Farangis, Jennifer Stiebich, Bruno K. Meyer, and Dietmar Hasselkamp — I. Physikalisches Institut, Justus Liebig Universität, Heinrich Buff Ring 16, 35392 Giessen

Metallic films of MgNi including a thin palladium cap-layer prepared by RF sputtering exhibit a reversible switching behavior from a highly reflecting to a transmitting state upon hydrogenation and dehydrogenation. The principle of a switchable mirror can be used in an optical sensor to detect hydrogen gas. It bases on a reversible metal-insulator-transition (MIT) upon hydrogen absorption. The MIT also changes the electrical conductivity, therefore in an electrical sensor, the change in conductivity can be used for hydrogen detection. The signal intensity before and after hydrogen take up (4% H₂ in Argon and at room temperature) is stable, and the hydrogen absorption is a fast process. It reaches for the optical sensor within 10 seconds 90% of the maximum value (t₉₀), and for the electrical sensor it is 1 second, considerably faster. The sensitivity of the sensors as a function of the hydrogen concentration was investigated (1-4% H₂ in Ar) and shows an exponential connection.