纳米锐钛矿相变的原位XRD研究

In situ XRD Study on the Phase Transformation of Nanoanatase

钛氧化物具有3种物相：锐钛矿、板钛矿和金红石，其中，锐钛矿和板钛矿为室温稳定相．在温度较高的条件下会向热力学更稳定的金红石相转变。锐钛矿向金红石的相变是热力学亚稳定相向稳定相的转变，由于这种相变过程不存在平衡温度．分析研究其相变过程无论从理论方面还是从实际应用方面均具有重要的意义。

The essence of the phase transformation of nanotitania is the change of the numbers of edges and corners shared by Ti-O octahedra. The microstructure characteristic of the anatase particle, such as the microstrain of lattice, affects its transformation to the rutile structure. In order to investigate the effect of the microstrain on nanoanatase transformation, phase pure anatase was prepared by sol-hydrolysis of TiCL in ammonium sulfate solution and its transformation process was investigated by in situ XRD. Based on the in situ XRD data, the variation of the diameter and its distribution, and the microstrain of the nanotitania particles were estimated with Win XRD software. The results show that the process of the transformation can be divided into four steps; the rate competition between the anatase growth and the transformation from anatase to rutile determines the size distribution and the diameter of anatase nanoparticles; and during the phase transformation, the microstrain determines the rates of the anatase and the transformation.