Solid oxide fuel cells (SOFC), which convert chemical energy of the incoming fuel to electricity via an electrochemical reaction, have become increasingly attractive to utility and automotive industries for a number of reasons, including their high efficiency and low emissions. Among different SOFC designs, the planar type is expected to be cost-effective, mechanically robust, and to offer high power density. As shown in Fig. 1, the interconnect is used in planar SOFC stacks to physically separate the fuel on the anode side from the air or oxidant on the cathode side. At the same time, the interconnect also functions as a bi-polar plate, electrically connecting adjacent ceramic membrane fuel cells in series in the stack. To make SOFC stacks function well, the interconnect has to be hermetically sealed to the adjacent components, such as cells and/or metallic frames which hold the cells. The sealing is often carried out using a glass-ceramic in the widely used rigid seal design. In order to maintain the structural stability and minimize degradation of SOFC performance, the sealing materials must be chemically compatible with the interconnect.