阳极氧化制备TiO_2纳米管阵列的可控相转变及表征

Controllable phase transformation of anodic TiO_2 nanotube arrays and its characterization

采用电化学阳极氧化法制备TiO2纳米管阵列，分别在02、N2、5％H2＋95％N2（体积分数）和NH3气氛中于400-650℃退火处理，初步实现TiO2纳米管中锐钛矿向金红石相转变的可控制备。采用FESEM、XRD、Raman对退火处理后TiO2纳米管的表面形貌、结构以及相转变等进行表征。结果表明：随着退火温度的升高，在O2气氛退火时，源于Ti基体的吞噬效应（Feeding effect）是导致TiO2相转变的主要原因；在N2和（5％H2＋95％N2）气氛退火后，氧空位加速了锐钛矿向金红石相的转变；而在NH3气氛中退火后，N掺杂则有效抑制了锐钛矿向金红石相的转变。在此基础上，对其相转变机理进行了初步探讨，为进一步制备具有可控相含量及微观点缺陷的TiO2半导体和高性能器件提供了有益思路。

TiO_2 nanotube arrays were prepared by electrochemical anodic oxidation method. Controllable anatase to rutile phase transformation （ARPT） was realized by annealing anodic TiO2 nanotube arrays （TNTs） in O2, N/, 5%H2＋95%N2 （volume fraction） and NH3 atmospheres at temperature range of 400-650 ℃. FESEM, XRD and Raman were used to characterize the surface morphology, structure and phase transformation of the annealed TNTs in different atmospheres and temperatures. The results show that the “feeding effect” is mainly responsible for the ARPT of TNTs annealed in O2 with increasing the annealing temperature. Oxygen vacancies induced by N2 and （5%H2＋95%N2） atmospheres accelerate the ARPT. Annealing in ammonia efficiently slows down the ARPT due to the N-doping. ARPT mechanisms were further investigated. These results provide us an efficient method to extend the study of synthesis of TiO2 semiconductors and high performance devices with controllable phase contents and point defects.