均匀准方形α-Fe_2O_3颗粒的制备

Preparation of Uniform Pseudocubic α Fe 2O 3 Fine Particles

用改进的凝胶溶胶法在 １００ ℃时陈化高浓度的 Ｆｅ（ Ｏ Ｈ）３ 凝胶制备窄粒度分布的准方形 α Ｆｅ２ Ｏ３ 颗粒， 并探讨成核过程及 α Ｆｅ２ Ｏ３ 的形成机制． 结果表明， 以 Ｆｅ Ｃｌ３ 溶液添加到 Ｎａ Ｏ Ｈ 溶液中的反向添加法， 在碱性条件下制备 Ｆｅ（ Ｏ Ｈ）３ 凝胶， 可提高 α Ｆｅ２ Ｏ３ 的成核率。

In order to raise the yield of the product and reduce the particle size, a modified gel\|sol method was used to prepare pseudocubic hematite particles with an exceedingly narrow size distribution by aging highly condensed ferric hydroxide at 100 ℃. When Fe(OH) 3 gel was prepared, in which initial molar ratio R 0 =[OH -] 0/[Fe 3+ ] 0=3, there were few free Fe 3+ ions in the gel, so particle size was significantly decreased, and the time for the reaction was shortened to less than 18 h. The nucleation process was studied, and the possible fromation mechanism of the hematite particles was discussed briefly. It was found that the morphology of the particles was markedly affected by the adding order of FeCl 3 and NaOH when they were combined in the first step to form Fe(OH) 3 gel. If the reversed adding method was used by adding FeCl 3 into a NaOH solution, the nucleation rate could be increased in a great degree, and the size was further decreased.