La2SrCr2O7: Controlling the Tilting Distortions of n = 2 Ruddlesden-Popper Phases through A-Site Cation Order.
Inorg Chem
; 55(17): 8951-60, 2016 Sep 06.
Article
en En
| MEDLINE
| ID: mdl-27505146
ABSTRACT
Structural characterization by neutron diffraction, supported by magnetic, SHG, and µ(+)SR data, reveals that the n = 2 Ruddlesden-Popper phase La2SrCr2O7 adopts a highly unusual structural configuration in which the cooperative rotations of the CrO6 octahedra are out of phase in all three Cartesian directions (ΦΦΦz/ΦΦΦz; a(-)a(-)c(-)/a(-)a(-)c(-)) as described in space group A2/a. First-principles DFT calculations indicate that this unusual structural arrangement can be attributed to coupling between the La/Sr A-site distribution and the rotations of the CrO6 units, which combine to relieve the local deformations of the chromium-oxygen octahedra. This coupling suggests new chemical "handles" by which the rotational distortions or A-site cation order of Ruddlesden-Popper phases can be directed to optimize physical behavior. Low-temperature neutron diffraction data and µ(+)SR data indicate La2SrCr2O7 adopts a G-type antiferromagnetically ordered state below TN â¼ 260 K.
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Colección:
01-internacional
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MEDLINE
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En
Revista:
Inorg Chem
Año:
2016
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Article
País de afiliación:
Reino Unido