Abstract: The present invention relates to a nitrogen oxide detecting element. Although there has been a demand for effecting detection of a nitrogen oxide by using a semiconductor type gas sensor, no semiconductor type sensors have existed which can detect the nitrogen oxide with good selectivity against other interfering gases (CO, H2) for an extended period of time with good durability. Then, by causing a gas detecting portion to include an oxide containing more than a predetermined amount of Bi and maintaining this gas detecting portion at a temperature range where its electron-conductivity is exhibited, it has become possible to detect the nitrogen oxide.

Abstract: A carbon monoxide sensor including a gas detecting portion and at least a pair of electrodes, wherein the gas detecting portion includes a metal oxide represented by a following formula;Cu.sub.1-x Bi.sub.x O.sub.y(0<x<1 and 1<y<1.5).

Abstract: A nitrogen oxide detecting sensor, according to the present invention, incorporates a gas detecting portion including, as a main component thereof, an oxide compound having electric conductivity or semiconductivity, the oxide compound having a crystal structure of 2212 phase and expressed generally as: Bi.sub.2 Sr.sub.2 (Ca.sub.1-x Y.sub.x)Cu.sub.2 O.sub.8.+-..delta. where 0.6.ltoreq.x<1; 0.ltoreq..delta..ltoreq.1. Electrodes are electrically connected to the gas detecting portion. When the gas detecting portion is analyzed by X-ray diffraction using cuK.alpha. rays to obtain diffraction peak values thereof in the range of a diffraction angle between 5.degree. and 65.degree., the diffraction peak values having a sum .SIGMA. I?2212! expressed by one of the following:(a) .SIGMA. I?2212!/.SIGMA. I?T!>88.1%(b) {.SIGMA. I?2212!+.SIGMA. I?2201!}/.SIGMA. I?T!>94.8%(c) {.SIGMA. I?2212!+.SIGMA. I?Y.sub.2 O.sub.3 !} .SIGMA. I?T!>88.1%(d) {.SIGMA. I?2212!+.SIGMA. I?(Bi, Ca) O!}/.SIGMA. I?T! >88.8%where .

Abstract: A nitrogen oxide sensor and a method of manufacturing the sensor are disclosed. The sensor has a gas detecting portion including sensitive material having electric property thereof subject to change in association with presence of nitrogen oxide in gas and a pair of electrodes electrically connected with the gas detecting portion. The gas detecting portion includes, as a main component thereof, metal oxide compound represented by a general formula:Bi.sub.2 Sr.sub.2 (Ca.sub.1-x Y.sub.x)Cu.sub.2 O.sub.8+y(0.8.ltoreq.x.ltoreq.1; 0.ltoreq.y.ltoreq.1)and having the 2212 phase crystal structure and crystalline size greater than 100 .ANG..

Abstract: A method of manufacturing a nitrogen oxide sensor for detecting a nitrogen oxide to be used in the field of e.g. reducing or decomposing nitrogen oxides, as well as such sensor and material suitable for manufacturing the sensor are disclosed. For manufacturing the sensor material, a precursor containing components for constituting the sensor material in a predetermined equivalent ratio of stoichiometry between chemical elements is prepared. First, the precurser is subjected to sintered to a preliminary sintering step. Then, the resultant sintered material is subjected to at least two cycles of main sintering step at 815.degree. to 848.degree. C. (T1) with an intermediate grinding step of the sintered material therebetween, thus obtaining the gas detecting portion comprised mainly of oxide compound having a composition represented by:Bi.sub.2 Sr.sub.2 YCu.sub.2 O.sub.8+y(0.ltoreq.y.ltoreq.1)and having the 2212 phase of crystal structure.