采用脉冲激光沉积的方法, 利用Zn0.95Co0.05O陶瓷靶, 在不同氧气压力下制备Zn1-xCoxO薄膜. 利用X射线衍射(XRD)、电子探针、吸收光谱对薄膜中Co含量、Co2+离子比例以及相组成进行了定量分析, 研究了沉积过程中氧气压力对薄膜中Co含量的影响, 定量讨论了薄膜中Co含量、Co2+离子比例以及相组成与薄膜室温磁性之间的关系, 分析了薄膜磁性的起源. 分析结果表明: 薄膜中Co含量随氧气压力增大而减少, Co以替位Co2+离子为主. 精细XRD分析表明, 薄膜中存在纳米尺度的金属Co团簇, 其含量与薄膜室温磁性估计的结果一致, Zn1-xCoxO薄膜的室温磁性归因于金属Co纳米团簇的超顺磁磁化机制.
Zn1-xCoxO films were deposited on Al2O3(001) substrates at different oxygen pressures with Zn0.95Co0.05O ceramic target by using pulsed laser deposition method. With X-ray diffraction (XRD), electron probe microanalysis (EPMA) and transmittance spectra, the contents of Co, Co2+ ions and phases in the films were quantitatively determined. The pressure dependence of Co contents in the films was given. The correlations between room-temperature magnetism and the Co, Co2+ ions and phases in the films are discussed quantitatively. It is found that the Co content in the film decreases with the increase of oxygen pressure during the deposition. Most of Co atoms are determined to be Co2+ ions entered the ZnO lattice to substitute for Zn2+ ions, but not being responsible for the magnetism of the films at room temperature. The metallic Co nano-clusters are detected by fine XRD analysis in the films deposited at 0.0001 Pa and 5.0 Pa, being consistent with the estimation using the room-temperature magnetism of the films. On the basis of quantitative analysis, a superparamagnetic magnetization mechanism of metallic Co nano-clusters is suggested and is compared with experimental results by quantitative calculation.
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