聚合物包覆的氧化锌纳米晶体的制备和表面标定

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

Preparation and surface indices of polymer-capped crystalline ZnO nano-crystallites

The understanding of the surface crystallography of nano crystallites is necessary for further applications as the properties of nano crystallites are no t 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 structure s for various advanced applications. PVP-capped ZnO nano crystallites were prepared v ia the colloid chemistry method. Most importantly with addition size-selective purification procedure the prepared ZnO nano-crystallites are of crystalline st ructure 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 Zn O nano-crystallites is about 4.5 nm in diameter according to the results of XRD w ith 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 imag es and corresponding Fourier transformation (FFT) taken from the ZnO nano crystalli tes, which distributed randomly on the TEM grid. It is found that the sketch of ZnO n ano 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-crystallit es 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.