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Phase stability study of Bi0.15Sr0.85-xAexCoO3-δ (x = 0 and Ae = Ba0.28; Ca0.17) perovskites by in-situ neutron diffraction

Annika K. Eriksson (Institutionen för kemi- och bioteknik, Oorganisk miljökemi) ; Sten G. Eriksson (Institutionen för kemi- och bioteknik, Oorganisk miljökemi) ; Laurent Chapon ; Christopher S Knee
Materials Research Bulletin (0025-5408). Vol. 45 (2010), 12, p. 1875-1882.
[Artikel, refereegranskad vetenskaplig]

The oxygen deficient perovskites, Bi0.15Sr0.85-xAexCoO3-δ, x = 0 and Aex = Ba0.28, Ca0.17, 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 Bi0.15Sr0.85CoO3-δ is shown to be dependent on temperature and the oxygen content of the phase, with three structural events, at T 250, 590 and 880 °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 900 °C the perovskite phase re-forms. For the Ba and Ca containing materials the decomposition to the hexagonal phase occurs at T 600 °C and 650 °C respectively. The presence of Ca at the A-site is found to stabilise the I4/mmm supercell structure in the range RT - 650 °C. The antiferromagnetic to paramagnetic transitions occur at TN 250 °C, TN 175 °C and TN 145 °C for the samples with Aex = Ba0.28, x = 0 and Aex = Ca0.17, respectively.

Nyckelord: Oxides, Neutron scattering, Phase transitions, Ionic conductor, TGA



Denna post skapades 2010-11-30. Senast ändrad 2011-12-13.
CPL Pubid: 129860

 

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Institutioner (Chalmers)

Institutionen för kemi- och bioteknik, Oorganisk miljökemi (2005-2014)
Institutionen för kemi (2001-2011)

Ämnesområden

Kemi

Chalmers infrastruktur