Stable, easily sintered Ca-Zn-doped YCrO₃ as novel interconnect materials for co-fired yttrium-stabilized zirconia-based solid oxide fuel cells

In order to develop co-fired yttrium-stabilized zirconia (YSZ)-based solid oxide fuel cells (SOFCs), stable and easily sintered Y_0.7Ca_0.3Cr_1-xZn_xO_{3- δ} (x = 0-0.15) perovskite oxides were synthesized by the microwave-aided sol-gel process and then examined as novel ceramic interconnect materials. (The characterizations focused on phase structure, sintering behavior, relative density, electrical conductivity and thermal expansion.) The XRD analysis indicates that a pure orthorhombic perovskite phase was obtained for all the samples. Cell volume decreases as x increases from 0 to 0.10. The Y_0.7Ca_0.3Cr_0.9Zn_0.1O _3-δ (YCCZ10) powder exhibited the best sintering ability, and a relative density of 96.6% could be obtained for the sample sintered at 1400 °C for 4 h in air. The electrical conductivities of the specimens increase with the Zn²⁺ content at x ≤ 0.10, but then remarkably decrease at x = 0.15, which might relate to the over-range of the substitution amount of Zn (0.15) for Cr position. YCCZ10 shows a remarkable electrical conductivity of 20.9 S cm^-1 at 850 °C in air, and a very suitable thermal expansion coefficient value of 10.8 × 10^-6 K^-1 (YSZ: ∼10.8 × 10^-6 K^-1). These investigations have indicated that YCCZ10 is a promising interconnect material for co-fired YSZ-based SOFCs.