Revisiting the Sr–Cr(IV)–O system at high pressure and temperature with special reference to Sr3Cr2O7

High pressure and temperature are used to synthesise perovskite related phases in the Sr–Cr(IV)–O system. The n = 1, 2 and ∞ members of the Srn+1CrnO3n+1 family have been obtained. Another new member, n = 3 as well as an hexagonal layered perovskite have also been observed by transmission electron microscopy and electron diffraction. The average structure of Sr3Cr2O7 as determined by XRD has space group I4/mmm, whereas its microstructure includes a large amount of defects both in the layer stacking and within the layers. 2D magnetism and a large electrical resistance in Sr3Cr2O7 are observed as opposed to the nonlocalized electronic behaviour of SrCrO3.

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