The Effect of High Pressure on the Defect Structure in the Nanocomposite Oxide Materials
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摘要: 详细研究了不同压力下压制的NiFe2O4纳米固体材料的正电子寿命谱，分析了材料内部界面上缺陷结构随压制压力的变化，并与La0.7Sr0.3MnO3纳米固体的缺陷结构随压力的变化进行了比较。实验结果表明，随着压制压力的增加，NiFe2O4纳米固体内部界面上自由体积缺陷和微孔隙缺陷的体积均被明显地压缩了，但自由体积缺陷的压缩幅度要高得多，反映出NiFe2O4纳米固体界面上原子排列的有序程度在高压下逐渐增强的规律。对具有不同微结构变化特征的复合氧化物纳米固体材料，其内部的缺陷结构在高压下具有不同的变化规律，进而引起其宏观物性的不同变化。Abstract: In this paper, the positron annihilation lifetime spectra of NiFe2O4 nanocrystalline materials compacted under different pressures (0～4.5 GPa) were measured. The variations of the defect structure of NiFe2O4 nanocrystalline with compacting pressure were analyzed and compared with those of La0.7Sr0.3MnO3 nanosolids with different microstructural characteristics. The size of the interface free volume and the microvoid in NiFe2O4 nanocrystalline were all compressed measurably under high pressure, but the former has higher compressibility. These changes mean that the arrangement degree of order of the interface atoms of NiFe2O4 nanocrystalline is enhanced gradually with the increasing of compacting pressure.
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Key words:
- high pressure /
- nanosolid /
- positron annihilation /
- defect structure
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Schaefer H E, Wurschum R, Birringer R, et al. Phys Rev B, 1988, 38(14): 9545. Sui M L, Lu K, Deng W. Phys Rev B, 1991, 44(12): 6466. Wurschum R, Soyez G, Schaefer H E. Nanostr Mater, 1993, 3: 225. KristiakovaK, KristiakJ, SausaO, etal. Key Eng Mat, 1993, 81-83: 215. 刘学东, 等. 科学通报, 1994, 39(5): 411. Sui Y, Xu D P, Zheng F L, et al. J Appl Phys, 1996, 80(2): 719. Su W H, Wu D M, Li X Y, et al. Physica B, 1986, 139-140: 658. Wurschum R, Greiner W, Schaefer H E. Mat Sci Forum, 1992, 105-110: 1337. Wurschum R, Greiner W, Schaefer H E. Nanostr Mater, 1993, 2(1): 55. 隋郁, 苏文辉, 郑凡磊, 等. 物理学报, 1997, 46(12). 郑凡磊, 隋郁, 许大鹏, 等. 髙压物理学报, 1997, 11(3): 209-214. Zheng F L, Sui Y, Xu D P, et al. (to be published elsewhere) -
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