Synthesis of sodium titanate composites by sol-gel method for use in gas potentiometric sensors

Mixtures of Na2Ti3O7/Na2Ti6O13 and Na2Ti6O13/TiO2 were synthesised by the sol-gel method using alkoxide precursors. XRD and SEM characterisations were performed. Semi-quantitative chemical analyses were carried out and the mixture ratio of Na2Ti3O7 /Na2Ti6O13 was 3:1 wt. A qualitative estimation on the mixture Na2Ti6O13/TiO2 gives also a higher ratio. Such composites are well suited to be used directly as oxygen electrode materials in potentiometric gas sensor devices exchanging sodium and oxygen with the surrounding phases. Electrochemical impedance spectroscopy (EIS) was used to measure the total conductivity. A part of electronic conductivity depending on the partial oxygen pressure was observed in the mixture Na2Ti6O13/TiO2 due to the presence of rutile TiO2.