Phase stability, single crystal growth, and anisotropic magnetic properties of Ca-La magnetoplumbite-type ferrite
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- 作者：K. Uji ; T. Waki ; Y. Tabata ; H. Nakamura ; nakamura.hiroyuki.2w@kyoto-u.ac.jp
- 关键词：Ca&ndash ; La magnetoplumbite-type ferrite ; Permanent magnet ; Single crystal ; Self-flux method ; Magnetic anisotropy ; Spin reorientation transition
- 刊名：Journal of Solid State Chemistry
- 出版年：2017
- 出版时间：January 2017
- 年：2017
- 卷：245
- 期：Complete
- 页码：17-22
- 全文大小：746 K
- 卷排序：245
文摘
The cation compositions in the Ca–La magnetoplumbite-type (M-type) ferrite, CaxLayFezO19, prepared from various initial fractions of reagents, were analyzed by wavelength-dispersive X-ray (WDX) spectroscopy. The reliability of the WDX composition analysis was confirmed by a crosscheck using inductively coupled plasma atomic emission spectrometry (ICP-AES). For particular polycrystalline samples furnace-cooled from 1250°C, the solubility ranges of Ca, La, and Fe were found to be 0.45≤x≤0.70,0.39≤y≤0.66, and 11.82≤z≤11.9211.82≤z≤11.92, respectively, assuming x+y+z=13x+y+z=13. Despite that the samples were synthesized from various starting compositions, the values of z/(x+y)z/(x+y) of the matrix M phase are smaller than the M-type regular value, 12, for all the samples and comes in a very limited range at ∼11∼11, suggesting most probably Ca occupation at particular Fe sites or Fe deficiency due to insertion of stacking fault to Ca/La/O packing. Single crystals of CaxLayFezO19 with various x/yx/y ratios were synthesized successfully by the self-flux method, followed by the characterization of their magnetic properties. The saturation magnetization and the Curie temperature were found to be almost independent of the cation composition. In contrast, the hard-axis magnetization process at low temperature depended significantly on the Ca/La ratio, and showed a sharp jump at ≲10≲10 kOe, which can be attributed to a spin reorientation transition associated with the appearance of Fe2+Fe2+.