Phase composition, size, orientation, and antenna effects of self-assembled anodized titania nanotube arrays: A polarized micro-Raman investigation
Phase composition, size, orientation, and antenna effects of self-assembled anodized titania nanotube arrays: A polarized micro-Raman investigation
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DOI：
10.1021/jp8027462
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发表时间：
2008-08-21
影响因子：
3.7
通讯作者：
Schmuki, Patrik
中科院分区：
文献类型：
--
作者：
Likodimos, Vlassis;Stergiopoulos, Thomas;Schmuki, Patrik
采用偏振显微拉曼光谱研究了自组织阳极TiO 2纳米管（NTs）的相组成、非晶态向晶态的转变、尺寸效应、晶体取向和天线偏振效应。的NT的形态特征量身定制的电化学阳极氧化在两种水溶液（磷酸盐缓冲液）和有机（乙二醇）电解质，以及在高氯酸盐/含氯电解质。生长后的热退火被证实显着减少封装在生长的阵列中的有机和无机物种，并驱动的非晶二氧化钛的纳米晶TiO 2的转变。通过改变在不同电解质介质中制备的TiO 2纳米管阵列的低频E-g声子模，研究了晶粒尺寸和形状效应以及氧的非化学计量比，并将结果与声子限制模型的预测结果进行了比较.偏振显微拉曼光谱识别部分取向效应，表明优先（101）生长的情况下，较短的二氧化钛纳米管（长度= 10 μ m）。独立NT膜的横截面上的偏振测量显示，当入射激光束的偏振平行于NT轴时，拉曼强度显著增强，表明归因于增强的光散射沿着圆柱形NT结构的“天线”效应。这种效应可以导致最佳的光学性质和选择性增强的电载流子的矢量输运。
Polarized micro-Raman spectroscopy was applied to investigate the phase composition and transformation from the amorphous to the crystalline state, size effects, and the crystallographic orientation and antenna polarization effects on self-organized anodic TiO2 nanotubes (NTs). The morphological characteristics of the NTs were tailored by electrochemical anodization in both aqueous (phosphate buffer) and organic (ethylene glycol) electrolytes as well as in perchlorate/chloride-containing electrolytes. Postgrowth thermal annealing was confirmed to reduce markedly the organic and inorganic species encapsulated in the as-grown arrays and drive the transformation of the amorphous titania to nanocrystalline anatase. Crystallite size and shape effects as well as oxygen nonstoichiometry were investigated through the variation of the low-frequency E-g anatase mode for the TiO2 NT arrays produced in different electrolyte media, and the results were compared with the predictions of the phonon confinement model for anatase nanoparticles. Polarized micro-Raman spectra identify partial orientation effects, indicating preferential (101) growth in the case of the shorter TiO2 NTs (length = 10 mu m). Polarized measurements on the cross section of free-standing NT membranes revealed significant enhancement of the Raman intensity when the polarization of the incident laser beam is parallel to the NT axis, indicating an "antenna" effect attributed to the enhanced light scattering along the cylindrical NT structure. Such an effect could result in optimum optical properties and selectively enhanced vectorial transport of electric carriers.