纳米TiO_2的相变及锐钛矿晶粒生长

Transformation of Anatase to Rutile and Anatase Grains Growth

通过 Ti Cl4 乳液水解法制备了纳米 Ti O2 颗粒 ,用 TG- DTA、XRD研究了相变和晶粒生长过程 .等温煅烧实验表明 ,锐钛矿的晶化从 6 2 3 K开始 ,而金红石相在 82 3 K形成 .纳米尺寸使相变的温度降低 ,锐钛矿晶粒的生长由于锐钛矿 -金红石相变的影响而分为两个不同表观活化能的温度段 ;低温段晶粒生长的活化能为 (2 2 .2 0± 1 .5 ) k J/mol;高温段晶粒生长的活化能为 (86 .88± 2 .2 )k

Nanosized TiO2 particles were prepared by the hydrolysis of TiCl4 emulsion. The phase transformation and grain growth process were characterized by TG-DTA and XRD analyses. The results of calcinating experiments show that the form of anatase begins at 623 K and rutile appears at 823 K in XRD spectra. Based on the Arrhenius plots, the apparent activation energies of anatase grains growth are (22.20±1.5) kJ/mol at the temperature below 773 K, and (86.88±2.2) kJ/mol at the temperature above 773 K, respectively.