The Influences of Sio2 on the Sintering Behavior and the Properties of Na+- Β/Β"-Al2O3 Solid Electrolyte

Abstract

SiO₂-doped Na⁺-β/β″-Al₂O₃ was synthesized via a solid-state reaction, and the relationship between the SiO₂ content and properties of Na⁺-β/β″-Al₂O₃ was investigated. Respective specimens were doped with 0 – 5 wt.% SiO₂ as a liquid phase sintering promotor and sintered. The specimens were characterized by XRD, SEM, densimeter and impedance analyzer. In the sintered samples, the phase fraction of β″-Al₂O₃ decreased as the SiO₂ content increased, whereas the relative sintered density was enhanced with the inclusion of less than 0.7 wt.% SiO₂. The relative sintered density of Na⁺- β/β″-Al₂O₃ sintered specimen with 0.7 wt.% SiO₂ doping reached 99.2 % of the theoretical density and the sintered density decreased when the amount of SiO₂ was larger than 1 wt.% result from excessive liquid-phase formation during sintering. Similarly, the ionic conductivity of SiO₂-doped Na⁺-β/β″-Al₂O₃ was enhanced by doping with a small amount of SiO₂, whereas the addition of more than 1 wt.% SiO₂ negatively affected the ionic conductivity of Na⁺-β/β″-Al₂O₃ due to a decrease in the sintered density and unfavorable phase relationship.

DOI: http://dx.doi.org/10.5755/j01.ms.25.3.14246