Yb(2)O(3) Doped Zr(0.92)Y(0.08)O(2-α)(8YSZ) and Its Composite Electrolyte for Intermediate Temperature Solid Oxide Fuel Cells

Yb(3+) and Y(3+) double doped ZrO(2) (8YSZ+4Yb(2)O(3)) samples were synthesized by a solid state reaction method. Moreover, 8YSZ+4Yb(2)O(3)-NaCl/KCl composites were also successfully produced at different temperatures. The 8YSZ+4Yb(2)O(3), 8YSZ+4Yb(2)O(3)-NaCl/KCl (800 °C), and 8YSZ+4Yb(2)O(3)-NaCl/KCl (1000 °C) samples were characterized by x–ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that a dense composite electrolyte was formed at a low temperature of 800 °C. The maximum conductivities of 4.7 × 10(−2) S·cm(−1), 6.1 × 10(−1) S·cm(−1), and 3.8 × 10(−1) S·cm(−1) were achieved for the 8YSZ+4Yb(2)O(3), 8YSZ+4Yb(2)O(3)-NaCl/KCl (800 °C), and 8YSZ+4Yb(2)O(3)-NaCl/KCl (1000 °C) samples at 700 °C, respectively. The logσ~log (pO(2)) plot result showed that the 8YSZ+4Yb(2)O(3)-NaCl/KCl (800 °C) composite electrolyte is a virtually pure ionic conductor. An excellent performance of the 8YSZ+4Yb(2)O(3)-NaCl/KCl (800 °C) composite was obtained with a maximum power density of 364 mW·cm(−2) at 700 °C.