The Crystal Structures, Microstructure and Ionic Conductivity of Ba2In2O5 and Ba(InxZr1−x)O3−x/2

✍ Scribed by P. Berastegui; S. Hull; F.J. Garcı́a-Garcı́a; S.-G. Eriksson

• Publisher: Elsevier Science
• Year: 2002
• Tongue: English
• Weight: 851 KB
• Volume: 164
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.2001.9455

✦ Synopsis

This paper describes the results of electron microscopy, high-temperature powder neutron di4raction, and impedance spectroscopy studies of brownmillerite-structured Ba 2 In 2 O 5 and perovskite structured Ba(In x Zr 1؊x )O 3؊x/2 . The ambient temperature structure of Ba 2 In 2 O 5 is found to adopt Icmm symmetry, with disorder of the tetrahedrally coordinated (In 3؉ ) ions of the type observed previously in Sr 2 Fe 2 O 5 . Ba 2 In 2 O 5 undergoes a &6-fold increase in its ionic conductivity over the narrow temperature range from &1140 K to &1230 K, in broad agreement with previous studies. This transition corresponds to a change from the brownmillerite structure to a cubic perovskite arrangement with disordered anions. Electron microscopy investigations show the presence of extended defects in all the crystals analyzed. Ba(In x Zr 1؊x )O 3؊x/2 samples with x ‫؍‬ 0.1 to 0.9 adopt the cubic perovskite structure, with the lattice parameter increasing with x.

2002 Elsevier Science (USA)