PREPARATION OF K2O-SM2O3-NSIO(2)-BASED SOLID-STATE ELECTROLYTE AND ITS APPLICATION TO ELECTROCHEMICAL CO2 GAS SENSOR

Ceramic-glass composites (K2O-Sm2O3-nSiO(2)) may be produced directly by the sintering of starting mixtures. The ionic conductivity is lower ed with an increase in SiO2 content for the sample with hexagonal stru cture. The CO2-sensing characteristics of an electrochemical gas senso r with a structure expressed as Pt\\K2O-Sm2O3-nSiO(2)\Na2CO3\\Pt, CO2 have been investigated in terms of a two-electron electrochemical reac tion. The e.m.f. is sensitive to the CO2 gas concentration and increas es with n in K2OSm2O3-nSiO(2). The introduction of water vapour induce s a lowering of the e.m.f. in which the decrement increased with a dec rease in CO2 concentration, and a prolongation of the response time. T he sensing characteristics recover completely after the water vapour i s cut off.