Crystal and Electronic Structures, and Oxide-Ion Conduction Path of Pr_1+xSr_1–xGa₃O_7+x/2

抄録

In this work, we focused on Pr_1+xSr_1−xGa₃O_7+x/2 with oxide-ion conduction, and investigated crystal and electronic structures of the materials by using neutron and synchrotron X-ray sources. In addition, we discussed oxide-ion conduction paths in the crystal on the basis of the results of the structural analyses. It was found by the Rietveld refinement that excess oxide ions were introduced into interstitial positions of the crystal and the interstitial oxide ions were located at a center of the Ga-O pentagonal ring in average. From nuclear density distribution obtained by the maximum entropy method, it was suggested that oxide ions diffused from O1 site to O3 site and/or from O3 site to another O3 site via the ring center and slightly off-centered positions. Such conduction paths of Pr_1+xSr_1−xGa₃O_7+x/2 are similar to that of La_1+xSr_1−xGa₃O_7+x/2, indicating an insignificant effect of the rare earths on the oxide-ion conduction property.