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A catalytic asymmetrical Nernst-type methane sensor with a porous Ni-CaZr 0.9 In 0.1 O 3Ϫ␣ Cermet electrode has been developed. At 600 and 700ЊC a Nernst-like behavior of the sensor is observed as a function of the methane partial pressure with a slope of 56 and 26 mV/decade, respectively. At 500ЊC a deviation from this behavior is found. The temperature dependence of the sensor response can be explained by the difference in catalytic activity of nickel and platinum. The sensor response depends on the CO 2 concentration, but it is shown that the measured electromotive force can be corrected for the CO 2 concentration in the gas mixture. The presence of water in the gas mixture leads to a decrease of the sensitivity, which can be explained by the different catalytic response of nickel and platinum to the presence of water. The sensor shows good reproducibility and long-term stability. The effect of the gas flow rate on the sensor performance is found to be minimal.

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A Wet-Chemical Method for the Synthesis of In-Doped CaZrO 3 Ceramic Powders. -A wet chemical method for In-doped CaZrO 3 ceramics is reported for the first time. A precursor is precipitated with (NH 4 ) 2 C 2 O 2 from a solution containing In 3+ , Ca 2+ , and Zr 4+ ions. XRD analysis after a first calcination step (air, 1273 K, 3 h) shows the coexistence of CaZrO 3 and CaIn 2 O 4 phases. The latter phase disappears after a second calcination step at 1823 K and CaZr 0.9 In 0.1 O 3−δ is formed. -(LE, J.; VAN RIJ, L. N.; VAN LANDSCHOOT, R. C.; SCHOONMAN, J.; J.