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摘要: 用原位角散X射线衍射实验装置研究了PbFe12O19在55.3 GPa压力以下的结构行为。通过拟合29.2 GPa以下的晶格参数随压力的变化得到线性压缩率Ba0=997(38) GPa, Bc0=556(22) GPa和体弹模量B0=254(8) GPa。线性压缩率的各向异性可归因于PbFe12O19的层状堆垛结构, 其较大的体弹模量可归因于致密的原子排列和较低的c/2a比。另外, 在42.7 GPa以上常压结构演变为另一种结构, 卸压至32.3 GPa以下时恢复到原来结构。Abstract: This work investigated the structural behavior of PbFe12O19 under high pressure by in situ angular dispersive X-ray diffraction (ADXD) measurements up to 55.3 GPa.The linear incompressibility Ba0=997(38) GPa and Bc0=556(22) GPa, and bulk modulus B0=254(8) GPa are obtained by fitting the Birch-Murnaghan equation of state with the unit-cell parameters versus pressure below 29.2 GPa.The anisotropic incompressibility can be attributed to the layered-stacking structure of PbFe12O19; the relative stiffness of PbFe12O19 can be ascribed to the dense atomic arrangement and the decreasing c/2a ratio.In addition, the ambient structure evolves to another structure above 42.7 GPa under compression and recovers below 32.3 GPa during releasing of pressure.
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Key words:
- compressibility /
- pressure-induced phase transition /
- PbFe12O19
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Figure 2. The compressibility of PbFe12O19 up to 29.2 GPa. (a) Pressure dependencies of the normalized unit cell volumes and lattice parameters; (b) Experimentally determined volume versus pressure (half filled squares)and the Birch-Murnaghan fitting (solid lines)
Figure 3. Process of pressure-induced phase transition.(a) The X-ray diffraction patterns before and after the phase transition and the changes of the diffraction peaks indicated by the arrows; (b) The X-ray diffraction patterns during releasing pressure and the changes of the diffraction peaks indicated by the arrows
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