Delacotte C, Hüe F, Bréard Y, Hébert S, Pérez O, Caignaert V, Greneche J M, Pelloquin D
Laboratoire CRISMAT ENSICAEN UMR CNRS 6508 , 6 Boulevard du Maréchal Juin, 14050 Caen Cedex 04, France.
Inorg Chem. 2014 Oct 6;53(19):10171-7. doi: 10.1021/ic5011456. Epub 2014 Sep 9.
An efficient synthesis route is proposed to obtain single phase powder ceramic of CaFe5O7. This complex structure can be described as an intergrowth between one CaFe2O4 unit and n = 3 slices of FeO Wüstite-type structure. A detailed structural study has been carried out at room temperature combining transmission electron microscopy (TEM) observations (ED, HREM), scanning transmission electron microscopy (STEM-HAADF), and X-ray diffraction data. The analysis of these data has revealed an unexpected supercell with a monoclinic symmetry. From the hkl conditions deduced from the electron diffraction study and the analysis of X-ray diffraction data by simulated annealing, a structural model considering the centrosymmetric P2₁/m setting can be proposed. In addition the first magnetic and electrical transport measurements are reported showing a sharp peak in magnetic susceptibility and a strong localization around 360 K, associated to a structural change from monoclinic setting to orthorhombic one.
提出了一种有效的合成路线来制备单相CaFe5O7粉末陶瓷。这种复杂结构可描述为一个CaFe2O4单元与n = 3片FeO方铁矿型结构的共生体。结合透射电子显微镜（TEM）观察（电子衍射、高分辨电子显微镜）、扫描透射电子显微镜（STEM-HAADF）和X射线衍射数据，在室温下进行了详细的结构研究。对这些数据的分析揭示了一个具有单斜对称性的意外超晶胞。根据电子衍射研究推导的hkl条件以及通过模拟退火对X射线衍射数据的分析，可以提出一个考虑中心对称P2₁/m设置的结构模型。此外，还报道了首次磁学和电输运测量结果，显示出磁化率的尖锐峰值以及在360 K左右的强局域化，这与从单斜设置到正交设置的结构变化有关。
