Effect of atomic layer deposition coatings on the surface structure of anodic aluminum oxide membranes
Effect of atomic layer deposition coatings on the surface structure of anodic aluminum oxide membranes
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DOI：
10.1021/jp0503415
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发表时间：
2005-07-28
影响因子：
3.3
通讯作者：
Stair, PC
中科院分区：
文献类型：
--
作者：
Xiong, G;Elam, JW;Stair, PC
采用原子层沉积(ALD)技术对阳极氧化铝(AAO)膜镀膜前后的全表面(包括内孔壁)进行了紫外拉曼光谱和红外光谱表征。紫外拉曼光谱显示，由于在阳极氧化过程中加入了酸性阴离子，所以在ALD涂覆Al_2O_3前后的AAO中都存在草酸铝。AAO中的草酸铝具有显著的热稳定性，在空气中不完全分解，直到暴露在&900℃的温度下才能完全分解。ALD被用来在AAO的表面覆盖氧化铝或二氧化钛。未包覆的AAO具有两种不同类型的羟基延伸的FT-IR光谱，分别归属于孤立的羟基和氢键表面的羟基。相反，ALD涂层的AAO表面显示出单一的、宽带的氢键OH基团。涂覆了二氧化钛的AAO基片表现出更为复杂的行为。紫外拉曼光谱结果表明，很薄的二氧化钛涂层(1 Nm)在500℃的温度下不稳定，而较厚的涂层可以完全覆盖被污染的氧化铝表面，并且在500℃以上是稳定的。
Anodic aluminum oxide (AAO) membranes were characterized by UV Raman and FT-IR spectroscopies before and after coating the entire surface (including the interior pore walls) of the AAO membranes by atomic layer deposition (ALD). UV Raman reveals the presence of aluminum oxalate in bulk AAO, both before and after ALD coating with Al2O3, because of acid anion incorporation during the anodization process used to produce AAO membranes. The aluminum oxalate in AAO exhibits remarkable thermal stability, not totally decomposing in air until exposed to a temperature > 900 degrees C. ALD was used to cover the surface of AAO with either Al2O3 or TiO2. Uncoated AAO have FT-IR spectra with two separate types of OH stretches that can be assigned to isolated OH groups and hydrogen-bonded surface OH groups, respectively. In contrast, AAO surfaces coated by ALD with Al2O3 display a single, broad band of hydrogen-bonded OH groups. AAO substrates coated with TiO2 show a more complicated behavior. UV Raman results show that very thin TiO2 coatings (1 nm) are not stable upon annealing to 500 degrees C. In contrast, thicker coatings can totally cover the contaminated alumina surface and are stable at temperatures in excess of 500 degrees C.