Accurate calculation and modeling of the adiabatic connection in density functional theoryWe identified a transversing physical connection between kinetic, exchange, and correlation functionals by using parameter-free ͑Pfree͒ exchange and one-parameter progressive ͑OP͒ correlation. On the basis of this connection, we investigated how the calculated energies and chemical properties depend on the shape of the functional in the Kohn-Sham scheme. We found that the fundamental conditions of the functionals are connected through Pfree and OP functionals with the exception of a rapidly varying density limit. We also found that the calculated properties are highly affected by the exchange functional shape in particular regions of x ϭٌ͉ ͉/ 4/3 .

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Mixed-potential-type gas sensors are promising solid-state devices for the in-situ detection of ppm concentrations of air pollutants in the atmosphere. In this study, we designed electrode structures of mixed-potential-type sensors using a BiCuVOx (Bi 2 V 0.9 Cu 0.1 O 5.35 ) solid electrolyte to control the responses of electrodes to organic gases. Devices fitted with sensing and counter electrodes made of a composite of BiCuVOx and a perovskitetype oxide (La 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3 ) were fabricated and tested for their ethanol-sensing properties. Sensor devices with a three-electrode configuration, in which a reference electrode was exposed to a standard air mixture, were fabricated to separately measure the potentials of the sensing and counter electrodes relative to the reference electrode. When a thin (30 µm) sensing electrode and a thick (68 µm) counter electrode were attached to a planar device, the sensing electrode exhibited high responses to ethanol at 350 and 400 °C. However, the overall signal was still small because the counter electrode also responded to ethanol. In another planar device in which the counter electrode was coated with a Pt/Al 2 O 3 catalyst, the counter electrode exhibited almost no response to ethanol resulting in the generation of large sensor signals. This is because the catalyst layer efficiently decomposed ethanol and impeded its diffusion to the reaction interface between the counter electrode and the solid electrolyte. The device coated with the combustion catalyst also showed good response and recovery speeds and high stability under humid conditions indicating its feasibility as a practical, compact ethanol sensor.

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