PHASE-STABILITY ACID ELECTRICAL-CONDUCTIVITY IN GD2TI2O7GD2MO2O7 SOLID-SOLUTIONS

Solid solutions in the Gd-2(Ti1-yMoy)(2)O-7 pyrochlore system, with y = 0.1, 0.3, 0.5, and 0.7, have been investigated as potential candidat es for the anode material of solid-oxide fuel cells, The electrical co nductivity, stability range, and optimal synthesis conditions of the p yrochlore phase have been explored by electrical, coulometric titratio n, and X-ray diffractometry techniques. As the molybdenum content incr eases, the maximum conductivity increases to a value of 70 S/cm for y = 0.7 at 1000 degrees C, whereas the stability range in the oxygen par tial pressure (p(O2)) decreases to just over two orders of magnitude i n p(O2) in the temperature range of 600 degrees-1000 degrees C. A deco mposition reaction that leads to decreased conductivity in oxidizing a tmospheres is proposed.