Potentiometric sensor for sulfur oxides using nasicon as a solid electrolyte
Abstract The ac conductivity of NASICON is higher by two orders of magnitude than that of Na2SO4 at 1000 K. The dc polarization measurement reveals that NASICON shows sodium ion conduction even at the temperature of about 1200 K, and that the electronic transference number is of the order of 10−5. The SO2-O2-SO3 concentration cell using NASICON electrolyte gives essentially the same electromotive force as in the cell using Na2SO4 electrolyte because a thin layer of Na2SO4 if formed on NASICON at the electrodes. The high sinterability of NASICON offers a dense electrolyte without permeation of gases. The SOx sensor using NASICON electrolyte exhibits good response and excellent selectivity against CO2 and NO2.