Microstructure control and properties of β"-Al2O3 solid electrolyte

Doping a small amount of TiO2 can promote the relative density, increase the content of beta ''-Al2O3 phase and improve the microstructure of beta ''-Al2O3 electrolyte. In this work, the influence of microstructure, relative density, content of beta '' phase and performance of beta ''-Al2O3 electrolyte were studied by adjusting the doping amount of TiO2 and the sintering temperature. Samples were characterized with respect of density, closed-cell porosity, XRD, SEM, bending strength, AC Impedance Spectroscopy. The results demonstrated that the addition of TiO2 can significantly improve the densification rate of beta ''-Al2O3 ceramics. 1500-1550 degrees C is the key temperature section of eliminating pore process. At 1550 degrees C, the sample of 0.1-0.8 wt.% TiO2 formed homogeneous microstructure associated with a refinement in the grain size of the final compact. Macro defects appeared when the sintering temperature reached to 1580 degrees C or the content of TiO2 was 1.6-2.0 wt.%. The total conductivity linearly depended on the temperature and fitted well with the Arrhenius equation. beta ''-Al2O3 ceramics showed the best bending strength and ionic conductivity at 1550 degrees C when the doping amount of TiO2 is 0.4 wt.% and 0.8 wt.%, respectively. (C) 2016 Elsevier B.V. All rights reserved.