CAJ | 학술논문

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.
납미정체적성질불부유표면원자소점적대적조분결정, 이차유정립표면적정상결구결정, 인차대납미정체적표면적정상결구적료해시흔유필요적. 양화자구유독특적물리화화학성질, 소이타피인위시일충비교유응용전경적3유유서조장결구적기본구조단원. 이용효체화학법화척촌선택제비료4～5 nm대소적PVP포복적양화자납미정체. 용X사선연사(XRD), 고분변투사전경(HR-TEM), 선구전자연사(SAED), 자외가견흡수광보(ABS)화형광광보(PL)대양화자적정체결구화표면정상결구진행표정, 발현양화자정체시결정흔호적홍자광결구병차척촌시단분산적. XRD, ABS화HR-TEM적측시결과도표명양화자정체적척촌시4.5 nm. 용HR-TEM화상응적부립협전환(FFT) 대양화자적형모화표면정상진행연구, 발현양화자정체구유절각륙면체형상,분별피{0001}, {0 1 1-0},화{0 1 1-1-}정면포위. 양화자적형광광보출현료량개전형적형광발사,위치분별재362 nm화527 nm, 래원우대변발사화결함발광. 령외재400 nm화470 nm처야출현료약적형광발사, 저가능여양화자적다면체형모혹자PVP적존재유관.
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.