Solid-state synthesis of high performance Na-β-Al2O3 solid electrolyte doped with MgO

The use of a small amount of MgO dopant can help to improve the performance of Na-beta ''-Al2O3 electrolyte by enhancing the relative density, promoting the formation of homogeneous and compact microstructure, and increasing the content of beta ''-Al2O3 phase. In this work, the effects of the amount of MgO dopant and the sintering temperature on the relative density, beta '' phase content, and performance of the Na-beta ''-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-beta ''-Al2O3 ceramics. The crucial temperature phase for pore elimination was 1500-1550 degrees C. Samples doped with 0.2-2.0 wt% MgO formed homogeneous microstructures associated with grain size refinement of the final compact at 1550 degrees C. Macro defects appeared when sintering temperature reached to 1580 degrees C. The total conductivity showed a linear dependence on the temperature (200-700 degrees C), which fitted well with the Arrhenius equation. Na-beta ''-Al2O3 ceramics doped with 0.4 wt% MgO showed the best bending strength (283 MPa) and preferable ionic conductivity. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.