Reducing the interfacial reaction between borosilicate sealant and yttria-stabilized zirconia electrolyte by addition of HfO2

Interfacial reactions between a sealing glass-ceramic and electrolyte present a challenge for the development of sealing materials. In this paper, we report for the first time, the interfacial reaction between Hf-containing borosilicate glass-ceramics and 8 mol.% yttria-stabilized zirconia (8YSZ) electrolyte. The results show that the interdiffusion between the glass-ceramics and the 8YSZ can be confined to a ∼2 μm zone at the interface. Additionally, the HfO2 dopant can inhibit the formation of monoclinic ZrO2 and zirconates in the reaction couples of glass-ceramics and 8YSZ, which can be attributed to the Hf-containing phase formation, e.g., Ca6Hf19O44 and Ca3HfSi2O9. Moreover, the formation of the Hf-containing phases contributes to a low conductivity of the glass-ceramics, e.g., 1.9 × 10−7 to 1.6 × 10−6 S cm−1 at 700 °C. These results demonstrate the suitability of the Hf-containing glass-ceramics as sealing materials for SOFC applications.