Zhang Ronghuan, Read Gareth, Lang Franz, Lancaster Tom, Blundell Stephen J, Hayward Michael A
Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford , South Parks Road, Oxford OX1 3QR, United Kingdom.
Department of Physics, Clarendon Laboratory, University of Oxford , Parks Road, Oxford OX1 3PU, U.K.
Inorg Chem. 2016 Mar 21;55(6):3169-74. doi: 10.1021/acs.inorgchem.6b00114. Epub 2016 Mar 9.
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 Cr(4+)O6 units. Typically materials containing networks of octahedrally coordinated Cr(4+) 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 Cr(4+) oxide phases are discussed.
通过拓扑化学氟插入反应，对n = 2的Ruddlesden-Popper相La2SrCr2O7进行低温氟化可生成La2SrCr2O7F2。氟化反应的结构守恒特性意味着初始氧化物相的铬中心在氟化产物中保留八面体配位环境，从而产生一种包含由顶点相连的Cr(4+)O6单元组成的扩展阵列的材料。通常，含有八面体配位Cr(4+)中心网络的材料只能在高压下制备；因此，La2SrCr2O7F2的制备表明低温拓扑化学反应为此类材料提供了一种替代合成途径。中子衍射、磁化和μ(+)SR数据表明，La2SrCr2O7F2在TN≈140 K以下转变为反铁磁态。讨论了该相和其他Cr(4+)氧化物相的结构-性能关系。
