射频磁控溅射方法制备掺氮TiO2薄膜及其结构和亲水性研究

Structural and Hydrophilic characteristics of N-doped TiOx films deposited by RF-Magnetron Sputtering

摘要:

本文采用磁控溅射方法制备掺氮TiO2薄膜。将TiO2作为靶材，通以N2/Ar混合气体来精确控制N的掺杂量。为改善掺氮TiO2薄膜的性能，首先将试样放于退火炉中退火，退火温度范围为300-600℃；再将试样放于黑暗处一段时间；最后用可见光（visible-light, VIS）照射。采用扫描电子显微镜（Scanning electron microscopy, SEM）观察薄膜的表面形貌，结果表明，颗粒尺寸随退火温度升高而增大。采用X射线光电子能谱（X-ray photoelectron spectroscopy, XPS）研究薄膜的化学成分，结果表明，薄膜中生成了N-Ti-O (β-N)和羟基，这可能是因为N掺杂入TiOx晶格引起的；且羟基含量随退火温度升高而增加，使得基片有更好的亲水性。采用X射线衍射（X-ray diffraction, XRD）研究薄膜的晶体结构，结果表明，退火后非晶薄膜转变为晶态。采用接触角仪测试薄膜的亲水性，结果表明，水接触角随退火温度升高而减小，这可能是由于颗粒尺寸和羟基含量的改变造成的。亲水性也受避光储存时间的影响，实验结果表明，随着储存时间的增加，水接触角增加。可见光照射实验表明，可见光照射后薄膜的亲水性增加。

Abstract:

In this work, nitrogen doped titanium oxides (N-doped TiOx) films were deposited by sputtering the TiO2 target in N2/Ar gas mixture to control the doping amount of nitrogen accurately. In order to modify the resultant films, the samples were annealed in air where the temperature ranged from 300 to 600℃, then they were irradiated under visible-light (VIS) after being placed in dark. X-ray photoelectron spectroscopy (XPS) spectra results showed that chemical composition of the films underwent the formation of N-Ti-O (β-N) and hydroxyl due to nitrogen doped into TiOx lattice. And the content of hydroxyl increased with annealing temperatures increasing, which led to the better hydrophilicity. X-ray diffraction (XRD) was used to investigate the crystallinity of the films annealed at different temperature and the results showed that the amorphous films transformed into crystalline phase as a consequence of annealing. Scanning electron microscopy (SEM) results showed that the particle size became bigger with the higher temperature. Hydrophilicity was tested by contact angle meter. The results showed that water contact angle decreased with the raising heat treatment temperature due to the change of particle size and the content of –OH. Hydrophilicity was also influenced by storing process, and the water contact angles increased with time. Furthermore, the hydrophilicity of N-doped TiOx films increased under visible light (VIS) irradiation.