CO[sub 2] Sensing Performances of Potentiometric Sensor Based on Na[sub 1+x]Zr[sub 2]Si[sub 2]PO[sub 12] (0<x<3)

Abstract

CO2 sensing characteristics were investigated under dry condition for potentiometric CO2 sensors: air, Au | NASICON (Na1+xZr2Si2PO12, x = 0, 1, 2, 2.75) | Li2CO3‐BaCO3, Au, air+CO2. The electromotive force (EMF) values of each NASICON sensor were linearly increased to the logarithm of CO2 concentrations in the range of 250 to 2500 ppm at 450° C. EMF values of each sensor continue to change toward negative potential during the operation exposing to 250 ppm CO2 under dry condition. For the sensor using NASICON (Na3.75Zr2Si2PO12) with rich Na component, base‐EMF (EMF value to fix a 250 ppm CO2) could become fairly stable. In addition, from the use of a x‐ray diffraction (XRD) measurements, the factor of EMF drifts caused the decrease of Na2O activity in NASICON by decomposition of NASICON components.