【摘要】 利用原位高温XRD方法测量了锐钛矿相TiO2在不同温度下(850、863、875、888、900℃)时间与转化率之间的关系,证实锐钛矿-金红石相转变为一级反应。计算的相转变活化能为432.788±25.657 kJ/mol,指前因子为4.847 454×1015 s-1。利用ESEM观察了样品在相转变完成后,经历不同温度(888、900、930、960、1 000℃)相同烧结时间(10 h),和相同温度(1 000℃)不同烧结时间(0、5、10、15、20 h)下颗粒晶型变化和颗粒长大情况。在1 000℃以下时,温度对颗粒粒度的影响并不明显,并且不出现完好的晶型。1 000℃时,随着时间的延长,颗粒粒度不断增大,并在10 h以后出现完好晶型。根据lnDt(Dt为t时间下颗粒的平均粒度)和lnt的关系图,认为颗粒生长应经过两个不同时期。更多还原

【Abstract】 Using in situ high temperature X-ray diffraction, the authors investigated the transformations from anatase to rutile at different temperatures(850, 863, 875, 888, 900℃). The experiment results of transition percentage versus time show that the conversion is first-order, and is characterized by an activation energy of432.788± 25.657 kJ/mol. The rate constants based on Arrhenius equation A is 4.847 454× 1015 s- 1. ESEM was used to find out the influence of temperature and time on grain size growth. Two experiment groups, transformation completed samples sintering at different temperatures(888, 900, 930, 960, 1 000℃)for 10 hours and transformation completed samples sintering at 1 000℃ for different periods of time(0, 5, 10, 15, 20 h),were studied. ESEM images show that at 1 000℃, the influence of temperature on grain size growth is not observable and fine crystal form of rutile does not exist. At 1 000℃, grain size grows with increasing time. Fine crystal form of rutile exists after sintering for 10 hours. The relationship between ln Dt(Dtis the average grain size in time t)and time shows that grain size growth has experienced two different periods.更多还原