液相法合成α-Fe_2O_3微粒及其成因分析

Preparation of Hematite Particles in Solution and the Analysis of Their Formation Process

本文研究了在沸腾回流条件下不同初始pH时由Fe(OH)3相转化为α-Fe2O3微粒的形成过程,结果表明:当pH低于4时,相转化过程需几十个小时方能完成,生成的α-Fe2O3的微粒尺寸分布较宽;而当pH为4-5左右时,相转化过程在几个小时内就可完成,生成的α-Fe2O3的微粒尺寸减小且分布范围较窄;当pH大于5以后,随着pH的升高,相转化时间又会延长。利用相关的热力学数据对上述结果产生的原因进行了分析并探讨了各种因素对制备均匀超细α-Fe2O3的微粒的影响。

The phase transformation process from Fe(OH)3 gel to α-Fe2O3 particles at different initial pH under the condition of boiling and refluxing was studied. The results showed that the phase transformation process is completed in tens of hours when pH < 4. The particles prepared under this condition are polydispersed. However, the phase transformation process is completed within a few hours when pH is between 4 and 5, and the size of the particles distributes within a narrow range. The necessary time for completing the phase transformation is prolonged when pH > 5. The cause resulting in the above results was analyzed by using the thermodynamic data. The effects of all kinds of factors on the preparation of α-Fe2O3 particles were discussed.