Preparation And Properties Of Lanthanum Zirconate-Based Electrolytes

La2Zr2O7, a typical pyrochlore oxide, has become a promising candidate for electrolyte of solid oxide fuel cells (SOFCs) with its unique properties. For study the proterties and filling the SOFCs requirements, La2Zr2-xMxO7 (M= Y, Sc, Er, Gd, Yb), La2-yNy Zr2O7(N=Ca,Sr,Mg,y≤0.06) and La2-ySryZr1.6Yb0.4O7 were prepared by conventional solid state reaction method. Through XRD analysis, microstructure observation, lattice parameter calculation and conductance measurement at temperature range of 500-1000°C in air, dry H2 and wet H2, respectively, it shows that in the La2Zr2-xMxO7 (M=Y, Sc) system, the conductivity increased with increasing the dopant levels at the beginning, at dopant level of x=0.4, it achieved the highest value, after that, it decreased with increasing the dopant levels; In the La2Zr1.6M0.4O7 (M= Y, Sc, Er, Gd, Yb) system, of the five dopant species, Yb is the most suitable tri-valence cation, and La2Zr1.6Yb0.4O7 has the highest electrical conductivities of 0.001 S/cm at 700°C in wet H2, which is higher than the previously reported results for Y-doped La2Zr2-xO7; In La2-yNy Zr2O7(N=Ca,Sr,Mg,y≤0.06)system, the conductivity increased with increasing the dopant levels. Another important factor influencing the conductivities is the soaking time during sintering. It is apparent that increasing the sintering time led to total conductivity increased.