Abstract
The use of a small amount of MgO dopant can help to improve the performance of Na-β″-Al2O3 electrolyte by enhancing the relative density, promoting the formation of homogeneous and compact microstructure, and increasing the content of β″-Al2O3 phase. In this work, the effects of the amount of MgO dopant and the sintering temperature on the relative density, β″ phase content, and performance of the Na-β″-Al2O3 electrolyte were studied in detail, respectively. The samples were characterized in respects of relative density, closed-cell porosity, XRD, SEM, bending strength, and AC Impedance. The results demonstrated that the addition of MgO dopant significantly improved the densification rate of Na-β″-Al2O3 ceramics. The crucial temperature phase for pore elimination was 1500–1550°C. Samples doped with 0.2–2.0wt% MgO formed homogeneous microstructures associated with grain size refinement of the final compact at 1550°C. Macro defects appeared when sintering temperature reached to 1580°C. The total conductivity showed a linear dependence on the temperature (200–700°C), which fitted well with the Arrhenius equation. Na-β″-Al2O3 ceramics doped with 0.4wt% MgO showed the best bending strength (283MPa) and preferable ionic conductivity.
Published Version
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