The Influence of Two-Step Sintering on the Hardness and Electrical Performance of Bi2o3-Ysz Composite Electrolyte

Abstract

A two-step sintering process was proposed for Yttria-Stabilized Zirconia doped bismuth oxide (Bi2O3-YSZ) electrolytes to suppress grain coarsening and oxygen vacancy regulation by controlling the first- and second-step sintering temperature (T1=1000~1100 °C, T2=800~900 °C) and also the holding time (2~6 h). This approach further reduced the sintering temperature, suppressed grain growth, and resulted in uniformly refined grains, improving the hardness value of the material. Additionally, low-temperature sintering minimized the volatilization of Bi2O3, which is beneficial for increasing the concentration of oxygen vacancies and conductivity of the electrolyte. Thus, fabricated sample exhibited an ionic conductivity of 0.098 S·cm-1 at 800 °C, which was three times of that (0.032 S·cm-1) of samples prepared by one-step sintering. This study provides an engineerable sintering strategy to simultaneously enhance hardness and ionic conductivity of Bi2O3-YSZ electrolytes, offering critical insights for advancing intermediate-temperature SOFC applications.

Keywords: Two-step sintering, Bi2O3-YSZ composite electrolyte, Hardness, Oxygen vacancy, Ionic conductivity