Yb₂O₃ Doped Zr 0.92 Y 0.08 O 2-α (8YSZ) and Its Composite Electrolyte for Intermediate Temperature Solid Oxide Fuel Cells.

Yb3+ and Y3+ double doped ZrO2 (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 degrees C), and 8YSZ+4Yb(2)O(3)-NaCl/KCl (1000 degrees 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 degrees C. The maximum conductivities of 4.7 x 10(-2) Scm(-1), 6.1 x 10(-1) Scm(-1), and 3.8 x 10(-1) Scm(-1) were achieved for the 8YSZ+4Yb(2)O(3), 8YSZ+4Yb(2)O(3)-NaCl/KCl (800 degrees C), and 8YSZ+4Yb(2)O(3)-NaCl/KCl (1000 degrees C) samples at 700 degrees C, respectively. The log sigma similar to log (pO(2)) plot result showed that the 8YSZ+4Yb(2)O(3)-NaCl/KCl (800 degrees C) composite electrolyte is a virtually pure ionic conductor. An excellent performance of the 8YSZ+4Yb(2)O(3)-NaCl/KCl (800 degrees C) composite was obtained with a maximum power density of 364 mWcm(-2) at 700 degrees C.