本實驗先以Stöber Process製備均一粒徑的球形二氧化矽粉體，並以滴定塗裝法（drop-coating）來製備蛋白石結構之膠體晶體。
由於膠體粒子在懸浮液中的分散狀態與其表面電位有關，而粒子表面之電位會因懸浮液不同的pH值而改變，實驗結果顯示加入少量NaCl或HCl來增加或降低粒子的表面電位，對於晶體的自組裝並無太大影響，但如添加過量的酸會因使得粒子表面電位過低，導致膠體粒子易產生凝聚現象而影響自組裝進行。另外自組裝進行過程中的溫度與相對濕度也會影響最後得到晶體的品質。由於懸浮液中的粒子因為布朗運動（擴散）的作用而無時無刻相互產生碰撞，溫度的升高會提高碰撞頻率，使最後無法得到有序的膠體晶體，然而過低的溫度會因粒子的自組裝動能不足也無法得有整齊排列的晶體，故溫度為影響滴定塗裝法自組裝的關鍵因素，且隨著膠體球粒徑的下降，最適合自組裝的溫度點亦隨之下降。此外，相對濕度對於自組裝膠體晶體結構亦有所影響，主要是因為它決定了蒸發速率的快慢。較高的相對濕度會因蒸發速率較慢，使液滴中間部分的粒子無法靠著蒸發作用所造成補償流被帶到液滴四周進行自組裝，隨著中間部分粒子濃度越來越高而導致粒子間的凡德瓦爾吸引力越大，產生凝聚現象，最後只能得到四周有序但中間混亂的晶體，此現象可藉由降低溼度、也就是提高蒸發速率來加以改善。且由實驗的結果顯示當在低相對濕度下，反應而得的膠體晶體有較均一的厚度，對於後續的分析與利用會較為有利。
本研究的第二部份則是探討以上由滴定塗裝法所製備的膠體晶體之光學性質。從光學性質的分析結果發現，本研究所製成之膠體晶體確實具有光子晶體特有的光子能隙現象，此能隙的波段與膠體粒子的大小及入射光的角度有關。當膠體粒子的粒徑由小變大時，能隙的波段會逐漸朝向高波長的方向移動；此外，能隙位置也會隨著入射光的角度變大，能隙位置向低波長方向移動。最後為了探討膠體晶體中膠體粒子與間隙之折射率比值的影響，將高折射率的二氧化鈦膠體溶液填入晶體之孔隙，並經過熱處理程序來改變二氧化鈦的折射率。實驗結果顯示膠體粒子與間隙之折射率比值為1.425時，具有光子能隙特性，且隨著折射率比值的提高，能隙位置會朝向高波長的地方移動。

The experiment is that we use the Stöber process to synthesize SiO2 particles of various sizes. Then, we use them to prepare the colloidal crystals of opal structure by the drop-coating method.
The dispersity of colloidal crystals in suspensions relies on the zeta potential. The zeta potential of colloidal particles is changed with the different pH of suspensions. It is founded that to add small amount of NaCl(aq) or HCl(aq) to adjust the zeta potential of colloidal particles does not affect the self-assembly of colloidal crystals. But if we add large amount of electrolyte, the aggregation will occur due to the decreasing of zeta potential. And this makes the self-assembly of colloidal crystals impossible. In addition, the temperature and the relative humidity in self-assembly procedure will also determine the quality of colloidal crystals. The colloidal particles in suspensions will collide each other all the time based on the Brownian motion. The increasing of reaction temperature will enhance the collision frequency of colloidal particles leading to receive disordered colloidal crystals. But when the reaction temperature is too low, the kinetic energy of colloidal particles is insufficient. And this also can not get ordered colloidal crystals. So the temperature of reaction is the key point to the drop-coating method. With the particle size decreases, the proper reaction temperature for self-assembly decreases too. Besides, the relative humidity also affects the structure of colloidal crystals because it affects the evaporation rate of the droplet. Due to Higher relative humidity represents lower evaporation rate, the colloidal particles in central area of droplet can not be brought to peripheral area of droplet. With the particle concentration increasing in central area of droplet, the Van der Waals attractive force between particles also increases. Finally, it can only get order array in peripheral area of colloidal crystal because of aggregation occurring in central area. This phenomenon can be improved by declining relative humidity or increasing evaporation rate. The experiment also found that the thickness of colloidal crystals is more uniform in low relative humidity condition. It would be benefit to the following analysis and application.
The second part of this research is to investigate the optical properties of colloidal crystals synthesized by drop-coating method. The optical analysis shows that there is a band gap in the photonic crystal. The photonic band gap is related to the size of colloidal particles and the incident angle of light. When the particle size increases, the photonic band gap will shift to high wavelength. However, when incident angle of light increases, the photonic band gap will shift to low wavelength. Finally, we discuss the refractive index ratio between colloidal particles and pores. Titanium dioxide with high refractive index will fill into the pores of colloidal crystals. And then changes the refractive index of titanium dioxide by way of heating treatment. The experiment represents that the refractive index ratio between particles and pores is 1.425, which has photonic band gap phenomenon. With the refractive index ratio increasing, photonic band gap will produce red shift.

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