利用掠角X光小角度散射法研究規則孔洞二氧化鈦薄膜結構

近年來多孔洞二氧化鈦材料陸續都有人們成功的合成出來，且在各領域也有長足的應用，但是規則的多孔洞二氧化鈦薄膜並不易製備。本研究以掠角小角度散射(GISAXS)分析不同的合成參數對於合成製備規則孔洞二氧化鈦薄膜材料之結構影響，在此使用溶膠凝膠法合成二氧化鈦材料並以高分子Pluronic P123為合成中所使用的軟模板，溶膠凝膠法裡水解與縮合速率扮演了結構改變非常重要的角色，透過使用蒸發誘導自組裝法(EISA method)使反應速率能與模板形成之速率做配合，達到不同結構，為此本研究改變了可以影響水解縮和反應的因素及條件如前驅物的種類、鹽酸濃度和溼度，而在模板方面也改變Pluronic P123濃度使其成型的速率與水解縮和反應做搭配。從實驗結果中也可以知到在Pluronic P123濃度為酒精溶劑10 wt%，且HCl/TTIP 莫耳比0.5的條件下能夠產生規則孔洞的二氧化鈦材料，形成之結構為平躺於矽基板表面的六方堆積結構(Hexagonal)，六角形邊的長度(Unit cell constant) a值為11nm，隨著Pluronic P123濃度的增加結構漸偏向於層狀堆疊的狀態(d = 9.81 nm)，此結果於Pluronic P123隨濃度增加之聚集結構變化相圖相似。在同一種模板溶液條件下改變施加的鹽酸量對於結構也會有很大的影響，濃度從高到低會形成的結構分別為球狀堆積成的柱狀結構(Cylinder)(d =14.61 nm )、柱狀體排列成的六方堆積(Hexagonal)(a = 11 nm)及最後一層層堆疊出的層狀結構(Lamella)(d = 9 ~11 nm)，值得一提的是這裡的柱狀堆積結構是垂直於基板表面，而六方堆積中的柱狀體則是平躺在矽基板上的。在改變了前驅物Ti(OBu)4後，也可以看到相似的結果，但是在六方堆積的結構中也摻雜了一些層狀結構在其中，因為水解速率較慢的原因使得模板可以形成較高濃度的結構，在使用EISA方法的過程中控制實驗於室溫下相對濕度50%和30%進行，從發現在當Pluronic P123濃度在5 wt%時兩者沒有太大差異，10 wt%時相對濕度30%的Hexagonal結構中也出現混有一些層狀結構的現象，當Pluronic P123濃度提到20 wt%時可以發現低濕度條件下，形成之Lamella結構的時間早於濕度較高的實驗。

關鍵字

多孔洞；二氧化鈦；軟模板；掠角小角度散射；溶膠凝膠

並列摘要

In this study, the effect of the synthesis parameters on the structure of the porous titanium dioxide thin films were investigated by Grazing-Incident Small-Angle X-ray Scattering(GISAXS). Sol-gel method was employed in this study to synthesize the porous titanium dioxide thin films using the polymer Pluronic P123 as the soft template. The hydrolysis and condensation rate of the precursor used in the sol-gel method play very important roles in controlling the synthesized structure. It is necessary to control these rates to allow the formation of ordered template structure. It is often need to use the evaporation-induced self-assembly method (EISA method) to successfully synthesize ordered porous titanium dioxide thin films. The factors affecting the hydrolysis and condensation reaction, such as the type of precursors, the concentration of hydrochloric acid, the humidity, and the Pluronic P123 concentration, were varied in this study. At Pluronic P123 concentration 10 wt%, and HCl/TTIP molar ratio 0.5, it was found that the synthesized titanium dioxide thin film possess hexagonal stacking structure, lying parallel to the silicon substrate surface with a unit cell constant of 11 nm. At higher P123 concentrations or higher acid conditions, it was found that the hexagonal structure is replaced by the lamellar structure. These findings suggest that the synthesized structures follow closely with the phase diagram of P123.

並列關鍵字

mesoporous ； TiO2 ； soft-template ； sol-gel ； GISAXS

參考文獻

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利用掠角X光小角度散射法研究規則孔洞二氧化鈦薄膜結構

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