Fabrication, characterisation and application of (8 mol% Y2O3) ZrO2 thin film on Na3Zr2Si2PO12 substrate for sensing CO2 gas

A planar type CO2 gas sensor employing (8 mol% Y2O3) ZrO2 (YSZ) thin film on Na3Zr2Si2PO12 (Nasicon) substrate with Na2CO3 as an auxiliary electrode has been fabricated and tested in laboratory environment between 700–900 K. The YSZ thin film was fabricated on Nasicon and alumina substrate using radio frequency (RF) magnetron sputtering. The film was examined using SEM and X-ray diffraction (XRD) after treating the Nasicon-YSZ bi-layer structure at 1300 K for 2 h. The results indicate that a crack free YSZ film was produced on Nasicon surface that was well bonded to the substrate. The conductivity of sputtered YSZ thin film measured by ac-impedance spectroscopy has been found to be higher than that of YSZ pellet by approximately half an order of magniture. The bi-electrolyte planar sensor displays rapid response (t95 ≤ 200 s) to CO2 compared to the tube type sensor (t95 ≤ 700 s) and the measured open circuit voltage of the electrochemical CO2 sensor has been found to be Nernstian at all temperatures. C 2005 Springer Science + Business Media, Inc.