Study On The Effect And Mechanism Of Iron-doped Titanium Dioxide Phase Transition By High-temperature In-situ XRD

As a non-toxic and harmless semiconductor material,titanium dioxide is widely used in photocatalytic and clean energy industries,and is also widely used in coatings and other industries due to its excellent whiteness and brightness.In order to make greater use of the excellence of titanium dioxide,people are keen to modify titanium dioxide to improve its performance.The crystal structure of titanium dioxide is mainly three kinds of structures: anatase,rutile and brookite,generally there are two kinds of anatase and rutile in practical application,different crystal structures have different applications,so the study of the crystal structure of titanium dioxide can better promote practical application.In this paper,Fe-doped TiO₂ was prepared by hydrolytic precipitation of Ti OSO4 and Fe Cl3·6H2O,and its phase transition laws and mechanisms were better studied by high temperature in-situ X-ray diffraction.The phase transition laws of Fe-doped TiO₂ were also studied using a combination of thermal analysis,X-ray photoelectron spectroscopy and Rietveld full-spectrum fitting,the Williamson-Hall method and phase transition kinetics,and the following main conclusions were obtained.1)The temperature of Iron-doped TiO₂ anatase to rutile phase transformation is higher than that of undoped TiO₂.The more Fe added,the higher the phase transition temperature,but the temperature at which the phase transition occurs to a certain concentration will stabilize.All A?R transitions of Fe content end at the same temperature,so Fe accelerates the phase transition process.However,Fe-doped suppresses the growth of the crystal size of TiO₂.The more iron-doped,the more obvious the crystal size suppression.2)The analysis of phase transformation kinetics and XPS showed that the phase transformation kinetics of Fe-doped TiO₂ was matched to the JMAK model,its phase transformation was controlled by the crystal defect,and Fe3+ in TiO₂ was reduced to Fe²⁺,generating oxygen vacancies,which promoted the phase change of TiO₂.In addition,the phase change of A?R is also affected by the size of the crystal.The phase A starts to grow after reaching a certain critical size?about 11 nm or more?.After Fe doping,it inhibits the growth of TiO₂ crystals and requires more energy to make the crystal size grow up,so the phase transition temperature is increased in the calcination at elevated temperature.