Thick films of NASICON (Na+ conductor, Na3Zr2Si2PO12) were prepared for the
fabrication of a planar CO2 sensor. The powder of a precursor of NASICON,
derived through a sol-gel process, was screen-printed on an alumina substra
te and converted into a NASICON thick film by calcination. The formation of
crystalline NASICON was almost complete after calcination at 900 and 1000
degreesC, but the films remained rather poor in densification. On the other
hand, the films were densified after calcination at 1100 degreesC or above
, but NASICON phase disappeared by decomposition. The planar CO2 Sensor dev
ice was thus fabricated by using the NASICON thick film (30 gm thick) calci
ned at 1000 degreesC. The device attached with a binary carbonate auxiliary
phase (Li2CO3-BaCO3) showed fairly good CO2 sensing properties at 450-600
degreesC. despite rather poor densification of the thick film used. (C) 200
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