Structural and electrochemical properties of La0.8Sr0.2Ga1−xFexO3

Mixed ionic-electronic conductor of Fe doped lanthanum gallate, La0.8Sr0.2Ga1−xFexO3, has been studied by the dc four-probe method and the neutron powder diffraction. In the electrical conductivity measurement at RT, insulator–metal transition-like phenomenon was observed at around x∼0.35; this suggests an existence of the percolation limit for the electronic conductivity. Simultaneously, a bond length between O atoms, lO–O, in a MO6 octahedron (MGa1−xFex) drastically expands over x∼0.4, according to the result of crystal structure refinement based on the hexagonal phase. Such a drastic expansion in the lO–O would induce the decrease in the oxygen ionic conductivity.