奈米氧化鋅之製備、微結構與發光特性之研究

Abstract

本研究藉由微乳液法合成奈米級氧化鋅螢光粉，其主旨在探討奈米螢光材料之製程、微結構及發光特性之相互關係。 微乳液法分為正相及逆相微兩類型，本論文分別採用此種配方以合成六方結構奈米氧化鋅微粒，最佳製程條件為350 ℃，燒成3.5小時。雷射粒徑分佈結果顯示，測得的奈米粒子尺寸範圍主要分佈在48~62 nm，平均粒徑為57 nm。而掃瞄式電子顯微鏡顯示，奈米粒子明顯地形成奈米團簇，另一方面，穿透式電子顯微鏡則顯示，大部分奈米粒子尺寸範圍在10~25 nm，最小粒徑尺寸達8~12 nm。 本論文嘗試調配不同比例的界面活性劑、油相及水相，並探討三者比例與奈米氧化鋅粒子尺寸、X射線繞射圖譜、光致發光光譜圖（PL）和CIE色度座標圖的相互關係。X射線繞射圖譜顯示：逆相微乳液系統中，界面活性劑的含量固定時，改變油相和水相的重量比，則所得奈米氧化鋅的X射線繞射圖譜最強繞射峰之半高寬隨水相含量增加而減小，且光致發光放射光譜圖在可見光範圍，放射峰波長呈現紅位移的現象。正相微乳液系統中，界面活性劑的含量固定時，當油相和水相之比例愈接近相圖中單相（A區域）中間區域時，則所得到的奈米氧化鋅產物其尺寸愈小，同時光致發光放射光譜圖，放射峰波長呈現藍位移的現象。

The goal of this research is to investigate the correlations among synthetic conditions, microstructures and luminescence for ZnO nanoparticles derived from microemulsion method. Normal and reverse microemulsion routes were adopted to prepared wurtzite ZnO nanoparticles and the optimal conditions were found to be 350℃ and 3.5 hr. The size of ZnO nanoparticles was found to be in the range of 48-62 nm with average size of 57 nm, as determined by laser light scattering method. On the other hand, the clustering of nanoparticles was apparently observed by SEM and as indicated by TEM micrographs, the size distribution lies in the range of 10-25 nm, which smallest particles obversed in the range of 8-12 nm. Both types of microemulsions with different proportions of surfactants:oli phase:water phase have been adopted to prepare ZnO nanoparticles, which were further characterized by the techniques such as X-ray diffraction (XRD), scanning and transmission electron microscopes (SEM and TEM), photoluminescence (PL) spectra, and CIE coordinates . We also tried to establish the correlation between microemulsion compositions and sizes of ZnO nanoparticles. As indicated by XRD, with decreasing content of oil phase:water phase ratio of the reverse microemulsion system, the FWHM of the strongest diffraction peak (200) was found to decrease and a red shift in emission wavelength (λem) in the visible range of PL spectra was also observed. With the ratio for oil:water content of the microemulsion system approaching the central region of the three-component phase diagram of p-xylene-glycerol-AOT, the size of ZnO nanoparticles was found to become smaller and the correspondingλem was observed to exhibit a blue shift in visible range of the PL spectra.