Semiconductor sensor for determn. of oxygen in exhaust gas - consists cerium di:oxide doped with other oxide, esp. magnesia or alumina

摘要

Parent patent describeda sensor for determn. of O2 and/or oxidisable gas, e.g. CO, which alter the conductivity of the semiconductor. In this addn., the sensor consists of CeO2, which is doped with MgO, Al2O3, Y2O3, TiO2, Ta2O5, Nb2O5, or V2O5. The CeO2 is pref. doped with 0.1-10 mole % of the oxide. The electric conducitivty of the sensor alters by at least 1 order of magnitude when the partial oxygen pressure in the total gas vol. alters by ca. half an order of magnitude. The semiconductor used in the main patent was very satisfactory when testing lean exhaust gas contg. 0.5-3% O2, but not in rich exhaust gas contg. CO. The present invention provides a highly sensitive semiconductor over the entire measuring range.