Direct-heated Gas Sensor by P-type Two Layers (zn, Mg)Cr<sub>2</sub>O<sub>4</sub>-TiO<sub>2</sub> Ceramics

This article consists of element structure with composition of ZMCT-25 and ZMCT-55 as two layers. ZMCT-25 is composition with a little content of TiO2, the sensitivity is high, the bondability of the electrode is low. On the other, ZMCT-55 is composition with much content of TiO2, the sensitivity is small, the bondability of the electrode is superior. Therefore, we found the possibility of the direct-heated gas sensor by an element with MCT-25 and MCT-55 as two layers structure. In addition, this clause describes sensor properties by the closed loop control using these two layers element and this element.