Phase stability study of Bi{sub 0.15}Sr{sub 0.85-x}Ae{sub x}CoO{sub 3-{delta}} (x = 0 and Ae = Ba{sub 0.28}; Ca{sub 0.17}) perovskites by in-situ neutron diffraction
- Department of Environmental Inorganic Chemistry, Chalmers University of Technology, SE-412 96 Goeteborg (Sweden)
- STFC, Rutherford Appleton Lab, ISIS Facility, Didcot OX11 0 QX, Oxon (United Kingdom)
The oxygen deficient perovskites, Bi{sub 0.15}Sr{sub 0.85-x}Ae{sub x}CoO{sub 3-{delta}}, x = 0 and Ae{sub x} = Ba{sub 0.28}, Ca{sub 0.17}, were studied with in-situ neutron powder diffraction and combined TGA/DSC in order to investigate their behaviour at elevated temperatures in oxidising conditions. The phase stability of the I4/mmm supercell structure adopted by Bi{sub 0.15}Sr{sub 0.85}CoO{sub 3-{delta}} is shown to be dependent on temperature and the oxygen content of the phase, with three structural events, at T {approx} 250, 590 and 880 {sup o}C, detected. The first transition occurs as the perovskite supercell vanishes due to oxygen absorption; the second transition is also associated with oxidation and involves the decomposition of the perovskite phase via an exothermic process to yield a dominant hexagonal phase. Finally, at T {approx} 900 {sup o}C the perovskite phase re-forms. For the Ba and Ca containing materials the decomposition to the hexagonal phase occurs at T {approx} 600 {sup o}C and {approx} 650 {sup o}C respectively. The presence of Ca at the A-site is found to stabilise the I4/mmm supercell structure in the range RT - 650 {sup o}C. The antiferromagnetic to paramagnetic transitions occur at T{sub N} {approx} 250 {sup o}C, T{sub N} {approx} 175 {sup o}C and T{sub N} {approx} 145 {sup o}C for the samples with Ae{sub x} = Ba{sub 0.28}, x = 0 and Ae{sub x} = Ca{sub 0.17}, respectively.
- OSTI ID:
- 22209952
- Journal Information:
- Materials Research Bulletin, Vol. 45, Issue 12; Other Information: Copyright (c) 2010 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0025-5408
- Country of Publication:
- United States
- Language:
- English
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