Zhang Lu, Luo Xian, Zhang Jian-Dong, Long Yong-Fu, Xue Xin, Xu Ben-Jun
College of Materials and Metallurgy, Guizhou University, Guiyang 550025, China.
ACS Omega. 2021 Jan 4;6(1):965-975. doi: 10.1021/acsomega.0c05609. eCollection 2021 Jan 12.
Titanium dioxide (TiO) is widely used in various major industries owing to its different crystal forms and functions. Therefore, fabricating suitable crystalline TiO through reasonable processes is necessary. In this study, Fe-doped TiO precursors were prepared via hydrolysis. Further, in situ high-temperature X-ray diffraction and transmission electron microscopy were used to transform the synthesized precursor in its crystal form. The Rietveld full-spectrum fitting method could accurately yield two different crystal forms at instant temperatures. Additionally, the rate relation between the crystal form transformation and reaction conditions was obtained. Results showed that the addition of Fe increased the temperature of phase transition of TiO anatase to rutile and accelerated the anatase → rutile transformation process. Further, crystal phase transition kinetic analysis showed that the phase transition kinetic model of Fe-doped TiO matched the Johnson-Mehl-Avrami-Kohnogorov (JMAK) model and that its phase transition was affected by crystal defects. Finally, Fe in Fe-doped TiO was reduced to Fe to generate oxygen vacancies, thus promoting the rate of transformation from titanium ore to rutile.
二氧化钛（TiO）因其不同的晶体形式和功能而广泛应用于各个主要行业。因此，通过合理的工艺制备合适的晶体TiO是必要的。在本研究中，通过水解制备了铁掺杂TiO前驱体。此外，利用原位高温X射线衍射和透射电子显微镜对合成的前驱体进行晶体形式转变。Rietveld全谱拟合方法能够在瞬间温度下准确地产生两种不同的晶体形式。此外，还获得了晶体形式转变与反应条件之间的速率关系。结果表明，铁的添加提高了TiO锐钛矿向金红石转变的温度，并加速了锐钛矿→金红石的转变过程。进一步的晶体相转变动力学分析表明，铁掺杂TiO的相转变动力学模型符合Johnson-Mehl-Avrami-Kohnogorov（JMAK）模型，其相转变受晶体缺陷影响。最后，铁掺杂TiO中的铁被还原为Fe以产生氧空位，从而提高了钛矿向金红石的转变速率。
