Figaro Engineering Inc.

Mariko Hanada

Kazunari Komatsu

Kazuo Okino

An exhaust gas sensor containing BaSnO.sub.3 or the like and a process for producing the sensor. The BaSnO.sub.3 is made free of segregation and adapted to have acid-base strength of at least 6.8 as determined with Hammett's indicator. Causes to reduce the acid-base strength of the BaSnO.sub.3 includes presence of Si and B, and causes to increase the acid-base strength include addition of Mg or Ca. The desired BaSnO.sub.3 can be prepared by precipitating BaSnO.sub.3 hydrous crystals while preventing introduction of Si and B thereinto especially with use of a container lined with a synthetic resin to prevent introduction of Si and B from the container, adding Mg or Ca to the precipitate, and thermally decomposing the precipitate.

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Nara, Japan

Mariko Hanada