In-situ diffraction study of Ba sub(2)In sub(2)O sub(5)

• Published in: Solid state ionics Vol. 149; no. 3-4; pp. 247 - 259
• Main Authors: Speakman, S A, Richardson, J W, Mitchell, B J, Misture, S T
• Format: Journal Article
• Language: English
• Published: 02.08.2002
• ISSN: 0167-2738

In-situ neutron and X-ray diffraction experiments were used to determine the crystal structure of Ba sub(2)In sub(2)O sub(5) as related to temperature. Ba sub(2 )In sub(2)O sub(5) has a Brownmillerite-type crystal structure from room temperature to 900 degree C, consisting of an orthorhombic unit cell with lattice parameters 6.0864(3)x16.7903(7)x5.9697(3) A and Icmm (74) space group symmetry. At 900 degree C, oxygen vacancies begin to disorder. By 925 degree C, barium indate crystallizes in a tetragonal, 6.0348(4) x17.0688(22) A, unit cell with I4cm (108) space group symmetry. This oxygen vacancy order-disorder transition is associated with an evolution to fast oxide-ion conduction. At 1040 degree C, Ba sub(2)In sub(2)O sub(5) becomes a cubic oxygen-deficient perovskite, 4.2743(1) A, in the Pm3m space group. At 1080 degree C, Ba sub(2)In sub(2)O sub(5) begins to decompose. copyright 2002 Elsevier Science B.V. All rights reserved.