Associate Professor Masatomo Yashima of the Interdisciplinary Graduate School of Science and Technology, Tokyo Institute of Technology (TITech), Dr. Katsuhiro Nomura and coworkers of the Special Division for Green Life Technology (GLT), National Institute of Advanced Industrial Science and Technology (AIST) and Mitsubishi Materials Corp. have successfully obtained the conduction path (or diffusion path) of oxide ions (O²-) in the fast oxide-ion conductor, doped lanthanum gallate (LaGaO₃). They have also deduced the temperature dependence of spatial distribution of oxide ions through the precise analysis of high-temperature neutron diffraction data, and succeeded in visualizing the conduction path of oxide ions in solid electrolyte, first in the world.

Lanthanum gallate is utilized as solid electrolyte material which is the key component of solid oxide fuel cells (SOFCs). The lanthanum gallate based SOFCs work at lower temperatures comparing with conventional YSZ-based SOFCs, and exhibit the highest efficiency in various SOFCs. The three groups in this collaboration have been making efforts for understanding the spatial distribution and the conduction path of oxide ions in the lanthanum gallate. The present results are expected to accelerate the performance upgrade and the R&D of SOFCs.

Conduction path and disorder of oxide ions (O²-) were obtained through the maximum-entropy method combined with Rietveld analysis using neutron powder diffraction data in the present study. A curved solid arrow (O1-O2) shows the conduction path of oxide ions. G represents the B-site cation gallium, magnesium and cobalt.

Figure. Conduction path and the spatial distribution of oxide ions in lanthanum gallate.

The result has been published in the international scientific journal, Chemical Physics Letters, (Elsevier Pub., the Netherlands) under the following title:

"Conduction path and disorder in the fast oxide-ion conductor (La_0.8Sr_0.2)(Ga_0.8Mg_0.15Co_0.05)O_2.8" Chem. Phys. Lett. 380: 391-396, October 2003.