Mixed ionic and electronic conduction in Mn/Mo doped gadolinium titanate

摘要

Recent work has shown that Gd_2(Ti_(1-x)MO_x)_2O_7 (Mo doped GT) exhibits high levels of mixed conduction under reducing atmospheres, making it suitable as an anode in a solid oxide fuel cell. It decomposes at high Po_2, however. We have succeeded in extending the stability limits of the GT-Mo to higher Po_2 with the addition of Mn. Our earlier studies on Gd_2((Mo_yMn_(1-y))_xTi_(1-x)_2O_7 (GMMT) as a function of Po_2, T, and composition utilizing impedance spectroscopy and X-ray diffraction are extended to include the joint effects of variations in x and y on the conductivity and stability of the material in cathodic environments. Defect models explaining the dependence of the partial conductivities on oxygen partial pressure, temperature and composition are also presented.