【摘要】 纳米晶体的性质不仅由表面原子所占的大的组分决定,而且由晶粒表面的晶相结构决定,因此对纳米晶体的表面的晶相结构的了解是很有必要的.氧化锌具有独特的物理和化学性质,所以它被认为是一种比较有应用前景的3维有序组装结构的基本构造单元.利用胶体化学法和尺寸选择制备了4~5 nm大小的PVP包覆的氧化锌纳米晶体.用X射线衍射(XRD),高分辨透射电镜(HR-TEM),选区电子衍射(SAED),紫外可见吸收光谱(ABS)和荧光光谱(PL)对氧化锌的晶体结构和表面晶相结构进行表征,发现氧化锌晶体是结晶很好的红锌矿结构并且尺寸是单分散的.XRD,ABS和HR-TEM的测试结果都表明氧化锌晶体的尺寸是4.5 nm.用HR-TEM和相应的傅立叶转换(FFT)对氧化锌的形貌和表面晶相进行研究,发现氧化锌晶体具有截角六面体形状,分别被{0001},{0 1 1 0},和{0 1 1 1}晶面包围.氧化锌的荧光光谱出现了两个典型的荧光发射,位置分别在362 nm和527 nm,来源于带边发射和缺陷发光.另外在400 nm和470 nm处也出现了弱的荧光发射,这可能与氧化锌的多面体形貌或者PVP的存在有关.更多还原

【Abstract】 The understanding of the surface crystallography of nano crystallites is necessary for further applications as the properties of nano crystallites are not only dependent upon the large portion of the surface atoms but also determined by the surface crystallographic structure.ZnO nano crystallites with unique properties have been accepted as the prospect building blocks of 3D ordered artificial structures for various advanced applications.PVP-capped ZnO nano crystallites were prepared via the colloid chemistry method.Most importantly with addition size-selective purification procedure the prepared ZnO nano-crystallites are of crystalline structure and 4～5 nm in diameter.The crystalline structure,surface crystallography and photoluminescence property of ZnO nano crystallites have been characterized with X-ray diffraction(XRD),high-resolution transmission electron microscopy (HR-TEM),selected area electron diffraction(SAED),UV-vis optical absorption spectroscopy and photoluminescence(PL).It is found that ZnO nano crystallites were highly crystallized in zincite structure and mono dispersed.The mean size of ZnO nano-crystallites is about 4.5 nm in diameter according to the results of XRD with the Debye-Scherrer theory,ABS and HR-TEM.The shapes and surface crystallography of the ZnO nano crystallites are studied in detail by analyzing the HR-TEM images and corresponding Fourier transformation(FFT) taken from the ZnO nano crystallites,which distributed randomly on the TEM grid.It is found that the sketch of ZnO nano crystallites was a truncated-hexagon pillar and surrounded with the planes of {0001},{0 1 1 0},and {0 1 1 1}.The PL spectra of ZnO nano-crystallites reveal that there are two typical PL emission bands at 362 nm and 527 nm,respectively,attributed to the near-band-edge emission and that of surface defects,as well.In addition,two weak emission bands can be found at 400 nm and 470 nm due perhaps to the polyhedral shape and/or the presence of PVP as well.更多还原