Phase Transition Behavior of the Layered Perovskite CsBi0.6La0.4Nb2O7: A Hybrid Improper Ferroelectric

The phase behavior of the layered perovskite CsBi0.6La0.4Nb2O7, of the Dion-Jacobson family, has been studied by high-resolution powder neutron diffraction between the temperatures of 25 < T < 850 °C. At ambient temperature, this material adopts the polar space group P21am; this represents an...

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Bibliographic Details
Published in:Crystals (Basel) 2017-05, Vol.7 (5), p.135
Main Authors: Dixon, Charlotte, McNulty, Jason, Knight, Kevin, Gibbs, Alexandra, Lightfoot, Philip
Format: Article
Language:English
Subjects:
Ambient temperature
Avalanches
Camber
Crystal structure
Diffraction
Ferroelectric materials
Group dynamics
High resolution
Neutron diffraction
Phase transitions
Temperature
Thermal evolution
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Summary:The phase behavior of the layered perovskite CsBi0.6La0.4Nb2O7, of the Dion-Jacobson family, has been studied by high-resolution powder neutron diffraction between the temperatures of 25 < T < 850 °C. At ambient temperature, this material adopts the polar space group P21am; this represents an example of hybrid improper ferroelectricity caused by the interaction of two distinct octahedral tilt modes. Within the limits of our data resolution, the thermal evolution of the crystal structure is consistent with a first-order transition between 700 and 750 °C, with both tilt modes vanishing simultaneously, leading to the aristotype space group P4/mmm. This apparent “avalanche transition” behavior resembles that seen in the related Aurivillius phase SrBi2Nb2O9.
ISSN:2073-4352
2073-4352
DOI:10.3390/cryst7050135