Thermal evolution of the crystal structure of the orthorhombic perovskite LaFeO3
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The thermal evolution of the crystal structure of the prototypical orthorhombic perovskite LaFeO3 has been studied in detail by powder neutron diffraction in the temperature range 25<T<1285 K. A conventional bond length/bond angle analysis, combined with an analysis in terms of symmetry-adapted modes, allows key aspects of the thermal behavior to be understood. In particular, the largest-amplitude symmetry modes (viz. in-phase and out-of-phase octahedral tilts, and A-site cation displacements) are shown to display relatively ‘normal’ behavior, increasing with decreasing temperature, which contrasts with the anomalous behavior previously shown by the derivative Bi0.5La0.5FeO3. However, an unexpected behavior is seen in the nature of the intra-octahedral distortion, which is used to rationalize the unique occurrence of a temperature dependent crossover of the a and c unit cell metrics in this compound.
Dixon , C A L , Kavanagh , C M , Knight , K S , Kockelmann , W , Morrison , F D & Lightfoot , P 2015 , ' Thermal evolution of the crystal structure of the orthorhombic perovskite LaFeO 3 ' Journal of Solid State Chemistry , vol 230 , pp. 337-342 . DOI: 10.1016/j.jssc.2015.07.019
Journal of Solid State Chemistry
Copyright © 2015 Published by Elsevier Inc. This work is made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://dx.doi.org/10.1016/j.jssc.2015.07.019
CALD and CMK were supported by EPSRC DTA studentships (EP/L505079/1).
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