Preparation of Na3Zr2Si2PO12–sodium aluminosilicate composite and its application as a solid-state electrochemical CO2 gas sensor

Abstract

A composite of sodium aluminosilicate and Na₃Zr₂Si₂PO₁₂ has been examined as a dense solid-state sodium-ion conductor. For the composite sintered at 1050 °C, the electrical properties are mainly based on those of Na₃Zr₂Si₂PO₁₂. When the composite was sintered at a higher temperature, the activation energy of the resistance increased toca. 55 kJ mol^–1 and the densification was well progressed with the formation of small zirconia particles. A good junction between the composite and Y-stabilized zirconia was achieved when the sintering was carried out at1175 °C. The formation of zirconia particles in the composite layer resulted in an enhancement of the mechanical strength at the junction. By using the ceramics, a solid-state electrochemical CO₂ sensor with an Na₂CO₃ layer was fabricated. Whilst the sensitivity of this sensor to CO₂ was slightly influenced by the coexistence of the water vapour in the test gas, a good sensing characteristic based on two-electron electrochemical reaction was confirmed.