Design and Processing of Environmental Gas Sensors Fabricated by Utilizing Decorative Technique on Pottery and Porcelain

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Fabrication of high-sensitive semiconductor gas sensors and application to other electronic devices by utilizing a slide-off transfer printing were attempted as below.1. Inflammable gas sensors Hetero-stacking of a pure SnO_2 layer over a Pt-loaded SnO_2 layer (SnO_2/Pt-SnO_2 sensor) led to the highest increase in H_2 sensitivity, whereas H_2 sensitivity of a Pt-SnO_2/SnO_2 sensor was much lower than that of the pure SnO_2 sensor. Stacking of a SnO_2-based layer over a TiO_2 layer also led to an increase in the H_2 sensitivity with a decrease in sensor resistance. On the other hand, NiO-loaded In_2O_3-based sensors showed high sensitivity to benzene and monochlorobenzene. Moreover, an SnO_2 sensor with a porous substrate layer (the porosity : ca. 56.2%) between the SnO_2 layer and a dense alumina substrate showed higher n-C_4H_<10> sensitivity compared with that fabricated directly on a dense alumina substrate.2. NO_x sensor Heterolayer Pt-Al_2O_3/WO_3 and Cr_2O_3-SnO_2 single layer se … More nsor were confirmed to operate as a total NO_x sensor ZnO-WO_3/ZnO sensor showed high NO_2 sensitivity and short response/recovery properties. In addition, introduction of a porous alumina sub-layer between a sensing layer and a dense substrate was effective to improve the NO_2 sensitivity and the response/recovery properties.3. Chemical surface modification of SnO_2 powder with ethoxysilane An SiO_2 thin film induced by the surface modification with diethoxydimethylsilane was found to exist as a grain-boundary phase from TEM observation. The limitation of neck growth between SnO_2 particles by the SiO_2 thin film coating is anticipated to be responsible for increasing the potential barrier height and improving the sensing properties to inflammable gases such as H_2, CH_4 and C_3H_8.4. Microstructure control of BaTiO_3 thick films Composition of a slurry containing BaTiO_3 fine powder prepared hydrothermally, some sintering aids, printing oil and 2-propanol was optimized for being utilized to a spin-coating technique. In consequence, dense and thick BaTiO_3 films (10-20μm) could be fabricated on a silicon substrate after calcination at 1050-1120℃. Less