Positron annihilation study of the interfacial defects in ZnO nanocrystals: Correlation with ferromagnetism
Positron annihilation study of the interfacial defects in ZnO nanocrystals: Correlation with ferromagnetism
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DOI：
10.1063/1.3291134
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发表时间：
2010-01
影响因子：
3.2
通讯作者：
Dong Wang;Z. Q. Chen;D. D. Wang-D.;N. Qi;J. Gong;C. Cao;Z. Tang
中科院分区：
文献类型：
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作者：
Dong Wang;Z. Q. Chen;D. D. Wang-D.;N. Qi;J. Gong;C. Cao;Z. Tang
将高纯度 ZnO 纳米粉末压制成颗粒，并在 100 至 1200 °C 的空气中退火。通过 X 射线衍射 2θ 扫描研究了 ZnO 纳米晶体的晶体质量和晶粒尺寸。随着温度从 400 °C 升高到 1200 °C，退火导致晶粒尺寸从 25 nm 增大到 165 nm。扫描电子显微镜和高分辨率透射电子显微镜观察也证实了退火过程中的晶粒生长。正电子湮没测量揭示了晶界区域的空位缺陷，包括锌空位、空位簇和空洞。在 100–700 °C 退火后，空隙很容易恢复。然而，正电子观察到的Zn空位和空位簇在低于500℃的温度下退火后保持不变，并在更高的温度下开始恢复。在高于 1000 °C 的温度下退火后，没有观察到界面缺陷导致的正电子捕获。拉曼光谱研究证实了晶格离散的恢复...
High purity ZnO nanopowders were pressed into pellets and annealed in air between 100 and 1200 °C. The crystal quality and grain size of the ZnO nanocrystals were investigated by x-ray diffraction 2θ scans. Annealing induces an increase in the grain size from 25 to 165 nm with temperature increasing from 400 to 1200 °C. Scanning electron microscopy and high-resolution transmission electron microscopy observations also confirm the grain growth during annealing. Positron annihilation measurements reveal vacancy defects including Zn vacancies, vacancy clusters, and voids in the grain boundary region. The voids show an easy recovery after annealing at 100–700 °C. However, Zn vacancies and vacancy clusters observed by positrons remain unchanged after annealing at temperatures below 500 °C and begin to recover at higher temperatures. After annealing at temperatures higher than 1000 °C, no positron trapping by the interfacial defects can be observed. Raman spectroscopy studies confirm the recovery of lattice dis...