Glass and glass-ceramics have been considered as the most suitable sealing materials. They are easy to fabricate and possible to prepare in a broad composition range. Glass and glass-ceramics, when applied to sealing materials in SOFC, should fulfill a number
of conditions, including thermal, mechanical, chemical and structural properties [8,10–12]. The potential requirements are: the glass transition temperature Tg should be below the operating temperature while relieving thermal stresses and self-healing cracks [13],the thermal expansion coefficient should be similar to the values of other fuel cell components between 8.0 and 13.0106
1C1[14–16], the resistivity should be high enough to protect electrica loss (4104
Ω cm), sealing should be tightly bonded not to allow any transportation of fuel gas and air to undesired components [7] When a sealant fulfills those conditions, it is commonly applicable
to different parts between electrodes/electrolyte (ceramics) andinterconnect/frame (metals). There often occurs devitrification in the glass and glass-ceramics when SOFC operates at high
temperature for a long time due to the crystallization of glass The inhomogeneous structural state by a devitrification gives rise to the reduction of the SOFC life-span, and thus a structural stability has to be considered for the development of the sealing glass and
glass-ceramics [13].