氧化物SrFeO_(3-δ)的可控制备与磁性(英文)

Tunable Synthesis and Magnetic Properties of Nano-shaped SrFeO_(3-δ)

应用熔盐路线通过控制温度和时间成功合成了微立方和纳米片层形貌的SrFeO3-δ化合物。X射线衍射、场发射扫描电子显微镜、透射电子显微镜和能量色散X射线光谱(EDS)以及热重分析(TGA)结果表明,微立方形貌化合物SrFeO2.86为四方相,空间群I4/mmm,纳米片层形貌化合物SrFeO2.62是钙铁矿(空间群Ibma)和正交相(空间群Cmmm)的复合物。磁学性能研究表明,SrFeO3-δ形貌对其性能有明显地影响;自旋失挫的减少与铁磁相互作用的增加密切关联;尽管成分几乎相同,但是形貌上的各向异性导致了明显不同的磁学性能。

SrFeO-δ products with microcube-shaped tetragonal type, and nano lamellae-shaped brounmiUerite and orthorhombic mixed type were successfully synthesized by a molten salt route through controlling temperature and time and lid-closure reaction. The synthesized products were systematically studied by X-ray powder diffraction, field- emission scanning electron microscopy, transmission electron microscopy, and energy dispersive X-ray spectroscopy as well as thermogravimetric analysis. The results show that the sample SrFeO2.86 has a tetrahedral symmetry with 14/mmm supereell. Evidence of weak superstructures, reflecting local oxygen ordering, is also obtained from electron diffraction. SrFeO2.62 was found to be a composite material by combination of a brownmillerite phase with Ibma space group and an orthorhombic structure with Cmmm space group. The results of magnetic properties indicate that the morphology of the SrFeO3-δproducts has great effects On their properties. Reduced spin frustration is associated with an increasing ferromagnetic interaction. The shape anisotropy results in distinct difference of magnetic properties in different oxides with nearly the same composition.