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Durham University

Department of Physics

Staff profile

Publication details for Professor Tom Lancaster

Zhang, R.H., Read, G., Lang, F., Lancaster, T., Blundell, S.J. & Hayward, M.A. (2016). La2SrCr2O7F2: A Ruddlesden–Popper Oxyfluoride Containing Octahedrally Coordinated Cr4+ Centers. Inorganic Chemistry 55(6): 3169-3174.

Author(s) from Durham

Abstract

The low-temperature fluorination of the n = 2 Ruddlesden–Popper phase La2SrCr2O7 yields La2SrCr2O7F2 via a topochemical fluorine insertion reaction. The structure-conserving nature of the fluorination reaction means that the chromium centers of the initial oxide phase retain an octahedral coordination environment in the fluorinated product, resulting in a material containing an extended array of apex-linked Cr4+O6 units. Typically materials containing networks of octahedrally coordinated Cr4+ centers can only be prepared at high pressure; thus, the preparation of La2SrCr2O7F2 demonstrates that low-temperature topochemical reactions offer an alternative synthesis route to materials of this type. Neutron diffraction, magnetization, and μ+SR data indicate that La2SrCr2O7F2 undergoes a transition to an antiferromagnetic state below TN ≈ 140 K. The structure–property relations of this phase and other Cr4+ oxide phases are discussed.