Synthesis and characterization of (Mg, Al)-doped apatite-type lanthanum germanate

In this study, (Mg, Al)-doped apatite-type lanthanum germanates were studied as a potential electrolyte for ITSOFC. La10 − xMg xGe5.5Al0.5O26.75 − x / 2 (x = 1.0, 0.6, 0.4, 0.2) were synthesized by solid state reaction. The phases of samples were determined by X-ray powder diffraction data using the Rietveld refinement and the lattice volumes increase with Mg doping amount. The conductivities obviously increase with Mg content below 600° C measured by impedance spectroscopy. The mechanism of oxygen ion migration is discussed.