EXAFS study of coordination structures of Gd-doped Ba2In2O5

Crystal structures of undoped and Gd-doped Ba2In2O5 were analyzed by EXAFS and the powder X-ray Rietveld method. Rietveld analysis indicated that Ba2In2O5 is belonging to orthorhombic Ibm2 space group and that Ba-2(In(1-x)Gdx)(2)O-5 (X = 0.20 and 0.30) is belonging to cubic Pm3m space group at room temperature. Foulier transform of In K-edge EXAFS of Ba-2(In(1-x)Gdx)(2)O-5 (X = 0.00, 0.20, 0.30) showed a peak between 1.2 and 2.0 Angstrom, attributed to the nearest oxide ions around In3+ cation. The peak was back-Fourier transformed, and the structural parameters were refined by the least square fitting. It was indicated that the coordination number of In3+ cation decreased with increasing Gd3+ cation content. This result indicates that coordination number of Gd3+ cation is not 4 but 6 preferably.