Preparation of Na-β″-Al2O3 solid electrolyte with nano-η-Al2O3 by double zeta process

Na-β″-Al2O3 was prepared with nano-η-Al2O3 powder by a double zeta process, MgO as stabilizer. The compactness, microstructure and mechanical properties of the samples were studied by Archimedes, SEM and three-point bending method, and the β″-Al2O3 phase content and ionic conductivity of the samples were studied by XRD and EIS. The results show that double zeta process is beneficial to improve the uniformity of sample structure. Nano-η-Al2O3 is easier to synthesize Na-β″-Al2O3 solid electrolyte than high purity α-Al2O3, the addition of appropriate MgO can increase the content of the β″-Al2O3 phase and the compactness of the samples, reduce the grain boundary resistance of the sample and improve the ionic conductivity of the electrolyte. Excessive MgO doping results in the growth of pore size in the samples, which will increase the grain resistance and decrease the ionic conductivity. The ionic conductivity of the electrolyte material reaches 0.0396 S·cm-1 at 300 ℃ when the amount of MgO is 2% (mass fraction).