High-temperature behavior of Sr-doped layered cobaltites Y (Ba1 - xSrx)Co2O5.5: phase stability and structural properties
Abstract
In this paper we present a neutron diffraction in situ study of the thermal evolution and high-temperature structure of layered cobaltites Y (Ba, Sr)Co2O5 + δ. Neutron thermodiffractograms and magnetic susceptibility measurements are reported in the temperature range 20 K <= T <= 570 K, as well as high-resolution neutron diffraction experiments at selected temperatures. Starting from the as-synthesized samples with δ≈0.5, we show that the room temperature phases remain stable up to 550 K, where they start losing oxygen and transform to a vacancy-disordered structure with tetragonal symmetry. Our results also show how the so-called '122' structure can be stabilized at high temperature (around 450 K) in a sample in which the addition of Sr at the Ba site had suppressed its formation. In addition, we present the structural and magnetic properties of the resulting samples with a new oxygen content δ≈0.25 in the temperature range 20 K <= T <= 300 K.
- Publication:
-
Journal of Physics Condensed Matter
- Pub Date:
- December 2010
- DOI:
- 10.1088/0953-8984/22/48/486001
- arXiv:
- arXiv:1007.3972
- Bibcode:
- 2010JPCM...22V6001A
- Keywords:
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- Condensed Matter - Materials Science;
- Condensed Matter - Strongly Correlated Electrons
- E-Print:
- doi:10.1088/0953-8984/22/48/486001