Structure and sealing properties of Bi_2O_3-BaO-SiO_2-R_xO_y glass

The sealing properties and structure of Bi2O3-BaO-SiO2-RxOy(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.