A cost-effective technique,including nanocrystalline powder preparation using a modified Pechini method and a two-step low-temperature sintering route,was developed for the synthesis of high performance La_2Mo_2O_9- based oxide-ion conductors.The optimum parameters of the compaction pressure,the first step and the second step sintering temperatures for the synthesis of fine grained,high density and uniform La_2Mo_2O_9- based oxide-ion conductors were determined by a series of sintering experiments.High density and uniform sintered La_2Mo_2O_9 samples with average grain size from 0.8 to 5μm and La_(1.96)K_(0.04)Mo_2O_(8.96) sample with average grain size as small as 500 nm were synthesized by using this cost-effective method.The impedance measurement results show that the as-fabricated La_2Mo_2O_9-based ceramics possess much higher ionic con- ductivity than that obtained by solid state reaction method.It is found that in the range of 0.8-5μm the grain size of dense La_2Mo_2O_9 samples prepared from the nanocrystalline powders has little influence on their conductivities.
