Kumar Chinthala Praveen, Gopal Neeruganti Obularajugari, Wang Ting Chung, Wong Ming-Show, Ke Shyue Chu
Physics Department, National Dong Hwa University, Hualien, Taiwan.
J Phys Chem B. 2006 Mar 23;110(11):5223-9. doi: 10.1021/jp057053t.
An in situ electron paramagnetic resonance (EPR) study has been carried out for anatase (Hombikat UV100) and rutile TiO(2) nanoparticles at liquid helium (He) temperature (4.2 K) under UV irradiation. Rutile titania was synthesized by ultrasonic irradiation with titanium tetrachloride (TiCl(4)) as the precursor. XRD and Raman results evidence the crystallinity of titania phases. The nature of trapped electrons and holes has been investigated by EPR spectroscopy under air and vacuum conditions. Illumination of TiO(2) powder (anatase and rutile) at 4.2 K resulted in the detection of electrons being trapped at Ti(4+) sites within the bulk and holes trapped at lattice oxide ions at the surface. The stability of electron traps was very sensitive to temperature in both phases of TiO(2). The annealing kinetics of the EPR detected radicals has been studied from 4.2 K to ambient temperature and also for calcined titania particles from 523 to 1273 K.
已在液氦（He）温度（4.2 K）下对锐钛矿型（Hombikat UV100）和金红石型TiO₂纳米颗粒进行了原位电子顺磁共振（EPR）研究，研究是在紫外光照射下进行的。以四氯化钛（TiCl₄）为前驱体通过超声辐照合成了金红石型二氧化钛。XRD和拉曼结果证明了二氧化钛相的结晶度。已通过EPR光谱在空气和真空条件下研究了捕获电子和空穴的性质。在4.2 K下对TiO₂粉末（锐钛矿型和金红石型）进行光照，结果检测到电子捕获在体相中的Ti(4+)位点，空穴捕获在表面的晶格氧化物离子处。在TiO₂的两个相中，电子陷阱的稳定性对温度非常敏感。已研究了从4.2 K到环境温度下EPR检测到的自由基的退火动力学，还研究了在523至1273 K下煅烧的二氧化钛颗粒的退火动力学。
