Ionic conduction in substituted scheelite-type oxide La2/3-xLi3xWO4

In order to obtain high ionic conductors, a new solid solution of La2/3-xLi3xWO4 with a scheelite-type structure was synthesized and the lithium ionic conduction were confirmed by electrochemical measurements and neutron radiography (NR). For pure La2/3WO4, the conductivity was about 10(-5) S cm(-1) at 900 degrees C. Enhanced conductivities are observed in the substituted samples. According to the oxygen gas concentration cell measurements and the electrolysis, it was found that tie main charge carriers are not electrons but ions for the substituted samples. From the NR images of electrolyzed La0.56Li0.30WO4 samples, furthermore, it could be obviously seen the lithium movement in the sample. From the profile of lithium, the lithium ion transport number of the oxide was known to be 0.67 at 900 degrees C, which would mean partly oxide ion contribution to the total electrical conduction.