球磨纳米TiO2的结构转变

采用X射线衍射研究锐钛矿型纳米TiO2在高能球磨过程中及球磨后的纳米TiO2在退火过程中的结构变化。结果表现在室温常压下高能球磨诱发锐钛矿相转变为金红石相和S相。随着退火温度升高，球磨纳米TiO2粉末的晶粒逐渐长大，锐钛矿相逐渐转变为金红石相，而S相并不直接转变为金红石相而是先转变为锐钛矿相，然后由锐钛矿相转变为金红石相。与未球磨的纳米TiO2相比，高能球磨导致的晶粒细化，显微畸变以及晶格缺陷密度的增加而引起的额外储能使球磨后纳米TiO2的锐钛矿相-金红石相转变温度明显降低。

Structure Transformation of Ball-Milled Mano-metre Scale TiO2

The structural evolution of nanocrystalline anatase TiO2 during high energy ball milling and after the ball milling during annealing was studied by means of ray diffractometer. It has been shown that mechanical activation induces the transformations from anatase to srilankite and rutile at room temperature and ambient pressure. During annealing, the crystallite size of the milled nanocrystalline TiO2 will increase with the rise of the annealing temperature. Srilankite, that is different from anatase, does not directly transform to rutile. Instead, srilankite firstly transforms to anatase and then anatase transforms to rutile. By comparison with the unmilled nanocrystalline Ti02, the temperature of the anatase - rutile phase transformation in the milled nanocrystalline TiO2 will be greatly decreased due to the additional energy caused by defects, lattice distortion and the refinement of the crystallite.