Ferromagnetic Properties of SrFe1−xCoxO3Synthesized under High Pressure
Ferromagnetic Properties of SrFe1−xCoxO3Synthesized under High Pressure
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DOI：
10.1006/jssc.1996.0025
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发表时间：
1996-01
影响因子：
5.4
通讯作者：
S. Kawasaki;M. Takano;Y. Takeda
中科院分区：
文献类型：
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作者：
S. Kawasaki;M. Takano;Y. Takeda
用氧化剂KClO4在6gpa和873 K下处理常压下获得的严重缺氧样品，制备了立方钙钛矿型的SrFe1−xCoxO3−δ(0≤x≤1,δ≤0.06)。通过x射线衍射测量确定了晶格参数，并用磁化强度和穆斯堡尔谱对其磁性进行了表征。高压处理发现，当0.4≤x≤0.9 （340 K atx= 0.6）时，铁磁居里温度高于300 K；当x≥0.4时，饱和磁化强度的成分依赖关系符合Fe4+离子与4 μBand Co4+离子1.8 μBalign的铁磁矩的简单图。SrFeO3的饱和超细磁场为330 kOe，随着Co含量的增加，超细磁场先快速下降（x≤0.15），然后缓慢下降至290 ~ 300 kOe，或呈指数型下降，表明Co取代倾向于在变宽的σ*带中使Fe亲本电子离域。SrFeO3是一种相对较低的反铁磁体，tsi为134 K， Sr2FeCoO6是一种高tsi为340 K的铁磁体，它们似乎代表了两个电子相在x= 0.1 ~ 0.15时从一个电子相切换到另一个电子相。
SrFe1−xCoxO3−δ(0 ≤x≤ 1, δ ≤ 0.06) of the cubic perovskite type was prepared by treating mixtures of grossly oxygen-deficient samples obtained at ambient pressure with an oxidizer, KClO4, at 6 GPa and 873 K. The lattice parameters were determined by X-ray diffraction measurements and their magnetic properties were characterized by measurements of magnetization and Mossbauer spectroscopy. The ferromagnetic Curie temperature has been found to be raised above 300 K for 0.4 ≤x≤ 0.9 (340 K atx= 0.6) by the high pressure treatment, and the composition dependence of saturation magnetization forx≥ 0.4 is consistent with a simple picture in which Fe4+ions with 4 μBand Co4+ions with 1.8 μBalign their moments ferromagnetically. The saturation magnetic hyperfine field, which is 330 kOe for SrFeO3, decreases quickly at first (x≤ 0.15) and then slowly to about 290 ∼ 300 kOe, or exponentially, as Co content increases, suggesting that the Co substitution tends to delocalize electrons of Fe parentage in a broadened σ* band. SrFeO3, an antiferromagnet with a relatively lowTNof 134 K, and Sr2FeCoO6, a ferromagnet with a highTCof 340 K, seem to represent the two electronic phases switched from one to the other atx= 0.1 ∼ 0.15.