Nippondenso Co., Ltd.

Shouzo Tanida

Tomio Sugiyama

Hiroshi Furuhashi

Hirohiko Tatumoto

An oxygen sensor has alumina porous layer on a surface of a solid electrolyte to cover electrodes and the alumina porous layer is simultaneously baked with the solid electrolyte. The alumina porous layer has baking contraction percentage which is the same range of the solid electrolyte. Alumina powder which is a starting material of the alumina porous layer includes 0.3 to 0.5 .mu.m of a 50% grain size, 0.4 to 1.1 .mu.m of a 70% grain size, and 0.8 to 4.0 .mu.m of a 90% grain size in a grain size distribution of weight integration frequency and further a specific surface area according to a BET method is approximately 8.5 to 11.0 m.sup.2 /g. It is preferable that the baking contraction percentages of the solid electrolyte and alumina porous layer are approximately 16 to 22%.

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Anjo, Japan

Shouzo Tanida