乙二醇甲醚体系中α-Fe_2O_3纳米晶制备与结构分析

Preparation and Structure Analysis of α-Fe_2O_3 Nanocrystalline in 2-Methoxyethanol System

研究了在硝酸铁乙二醇甲醚溶液体系中，用溶胶－乳化－凝胶法制备氧化铁纳米晶，首次将表面活性剂（ＳＤＳ）引入溶胶－凝胶化过程，并采用一种高效缩合催化剂来加速此过程．结合ＴＥＭ、ＸＲＤ和ＴＧ－ＤＴＡ分析手段对产物进行了表征，结果表明，加入的表面活性剂（ＳＤＳ）有助于纯相α－Ｆｅ２Ｏ３纳米晶的生成，而缩合催化剂钛酸了酯的加入则大大缩短凝胶时间，所得粉体的原始晶粒尺寸为３０ｎｍ左右．若以常用的硅酸乙酯代替钛酸丁酯，则胶凝时间明显延长，最终产物为β和α氧化铁的混晶相（γ－Ｆｅ２Ｏ３为主晶相），晶粒尺寸约为１０ｎｍ，并从中提出了一条改进γ－Ｆｅ２Ｏ３基气敏材料性能的新思路．

The nanocrystal α-Fe2O3 with an average size of about 30 nm was prepared by a sol-emulsify-gel method in the iron nitrate and 2-methoxyethanol system. The powders were characterized by TEM, XRD and the xerogel primary powders thermal stability was studied by TDTA. The gelation time was reduced greatly by adding tetrabutyl titanate. When tetraethyl orthosilicate instead of tetrabutyl titanate, the gelation time can be much longer. γ-Fe2O3 with spinel structure appeared as the main phase in the calcinated powder and the average particle size was about 10 nm. A new idea to improve the gas sensitivity and stability of γ-Fe2O3 gas-sensitive materials was provided. The results show that the introduction of surfactant(SDS) is helpful to form pure crystal phase α-Fe2O3.