Open AccessEXAFS study of crystal structures of (Ba 1−x La x ) 2 In 2 O 5+x and their oxide ion conductivity
Author(s) -
Uchimoto Yoshiharu,
Takagi Hiromitsu,
Yao Takeshi,
Ozawa Naoshi,
Inagaki Toru,
Yoshida Hiroyuki
Publication year - 2001
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s090904950002094x
Subject(s) - extended x ray absorption fine structure , analytical chemistry (journal) , perovskite (structure) , crystal structure , rietveld refinement , oxide , chemistry , conductivity , ion , vacancy defect , electrical resistivity and conductivity , coordination number , phase (matter) , doping , inorganic chemistry , crystallography , materials science , absorption spectroscopy , physics , optoelectronics , organic chemistry , chromatography , quantum mechanics
Crystal structures of (Ba 1−x La x ) 2 In 2 O 5+x (x=0.00, 0.20, 0.30, 0.40, 0.50) were analyzed by EXAFS and the powder X‐ray Rietveld method. A Fourier transform of In K‐edge EXAFS data from (Ba 1−x La x ) 2 In 2 O 5+x showed a peak between 1.2 and 2.0 Å attributed to the nearest oxide ions around In 3+ cation. The peak was back‐Fourier transformed, and the structural parameters were refined by the least square fitting. The coordination number of In 3+ cation increases with increasing La 3+ cation content. This means oxygen is introduced at interstitial site by keeping an electroneutrality. As a result of the oxygen distribution, the oxide ion vacancies distribute randomly. The electrical conductivities of (Ba 1−x La x ) 2 In 2 O 5 rapidly increased above 1203 K due to the order–disorder transition of oxygen vacancy. On the other hand, the electrical conductivities of (Ba 1−x La x ) 2 In 2 O 5+x (x=0.20, 0.30, 0.35, 0.40, 0.45, 0.50) did not show the sharp discontinuity in the conductivity because the disorder phase of defective perovskite type structure was stabilized by doping La 3+ cations at A‐site even at low temperature.