Structure and sealing properties of Bi₂O₃-BaO-SiO₂-R_xO_y glass

The sealing properties and structure of Bi₂O₃-BaO-SiO₂-R_xO_y(Bi-Ba-Si-O) glass were studied for fabricating solid oxide fuel cells(SOFC).The density functional theories(DFT) were employed for the structure optimization of Bi₂O₃ into SiO₂ glass networks,and was theoretically determined to be the most possible structure of bismuth as interconnections in the Bi-Ba-Si-O glass.The functions and possible existence structures of Ba²⁺ and Al³⁺ were also discussed.According to experimental investigations,the coefficient of thermal expansion(CTE) of the Bi-Ba-Si-O glass is 11×10^-6K^-1(50 to 530℃) which can be matched with the YSZ electrolyte(CTE:10.2×10^-6K^-1) and the SUS430 steel metallic interconnect(CTE:11.3×10^-6K^-1).Data form XRD analysis show that the Bi-Ba-Si-O glass is amorphous and consistent with the theoretical analysis.When the Bi-Ba-Si-O glass is used as sealing materials for SOFC,the glass,the SUS430 metallic interconnect and the YSZ electrolyte adhere well with good air-tightness.It is concluded that the Bi-Ba-Si-O glass can meet the requirements of SOFC sealing materials.