POLAR NANO-REGIONS IN STRONTIUM STANNATE

We recently used total scattering experiments to discover polar nano-regions (PNRs) in SrSnO3. Planar ferroelectric domains approximately 10–15 Å in diameter emerged during reverse Monte Carlo refinements. These gave rise to characteristic diffuse scattering patterns very similar to those observed experimentally for relaxor ferroelectrics.

PNRs are known to play a key role in relaxor behaviour, such as in the technologically-important material PbZn1/3Nb2/3O3 (PZN). But it had always been thought that their existence is coupled to local variations in cation ordering (e.g. Zn/Nb ordering in PZN). What is particularly exciting about the discovery of PNRs in SrSnO3 is that there is no scope for cation ordering processes in this material, meaning that B-site disorder is not absolutely required for PNR formation. Moreover, while SrSnO3 itself does not show relaxor behaviour, this result does open the possibility that Pb-free relaxors may yet be found in surprisingly simple systems.

Ferroelectric nanoscale domains and the 905 K phase transition in SrSnO3: a neutron total-scattering study. Phys Rev B 76, 174114 (2007)

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