%0 Journal Article
%A García Martín, Susana
%A King, Graham
%A Nénert, Gwilherm
%A Ritter, Clemens
%A Woodward, Patrick
%T The incommensurately modulated structures of the perovskites NaCeMnWO6 and NaPrMnWO6
%D 2012
%U https://hdl.handle.net/20.500.14352/130435
%X The structures of the doubly ordered perovskites NaCeMnWO 6 and NaPrMnWO 6 , with rock salt ordering of the Mn 2+ and W6+ B-site cations and layered ordering of the Na + and (Ce 3+ /Pr 3+) A-site cations, have been studied by transmission electron microscopy, electron diffraction, neutron and synchrotron X-ray powder diffraction. Both compounds possess incommensurately modulated crystal structures. In NaCeMnWO 6 the modulation vector (with reference to the ideal ABX3 perovskite subcell) is q ≈ 0.067a* (∼58.7 Å) and in NaPrMnWO6 q ≈ 0.046a* (∼85.3 Å). In both compounds the superstructures are primarily the two-dimensional chessboard type, although some crystals of NaCeMnWO 6 were found with one-dimensional stripes. In some crystals of NaPrMnWO6 there is a coexistence of chessboards and stripes. Modeling of neutron diffraction data shows that octahedral tilting plays an important role in the structural modulation
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