表面修饰对α-Fe2O3超微粒光谱特性的影响

本文用超声分散的方法将α Fe2 O3 超微粒分散于硬脂酸 /正己烷 /氯仿溶液中 ,使α Fe2 O3 超微粒被硬脂酸表面修饰。α Fe2 O3 超微粒被表面修饰后 ,紫外 可见光的吸收边从 392nm移动到 896nm ;红外光谱中的Fe—O键振动峰出现了“红移”现象 ,分别从 52 4 36cm- 1 移动到 52 1 33cm- 1 和从 446 37cm- 1 移动到 443 34cm- 1 ,表面修饰后 ,α Fe2 O3 超微粒X 射线衍射的相对强度明显增大 ,衍射峰位置向衍射角减小的方向移动。

Effect of Surface Decoration on the Spectral Characteristics of α-Fe2O3 Ultrafine Particles

The alpha-Fe2O3 ultrafine particles were equally dispersed in the solutions of stearic acid/n-hexane/chloroform by the ultrasonic method, the surfaces of the alpha-Fe2O3 ultrafine particles were decorated by stearic acid, and the alpha-Fe2O3 ultrafine particles decorated had very good flowage characteristic. Before alpha-Fe2O3 ultrafine particles were decorated, the UV absorption was very strong at wavelengths shorter than 290 nm, and there was a shoulder peak at 330 nm. The absorption band edges of alpha-Fe2O3 ultrafine particles was at 392 nm, and shifted toward blue, which was in contrast with that of bulk Fe2O3. This was caused by the quanta size effect and surface effect. IR characteristic peaks of the alpha-Fe2O3 ultrafine particles appeared at 524.36 and 446.37 cm-1. After alpha-Fe2O3 ultrafine particles were decorated, the absorption side moved from 392 to 896 nm, which significantly shifted to the red in contrast with that of bulk F2O3. The vibration of Fe-O bond moved from 524.36 to 521.33 cm-1 and from 446.37 to 443.34 cm-1, respectively. These were caused by the dielectric confinement effect. The relative intensity of X-ray diffraction obviously increased, and the diffraction peak size moved toward the direction of smaller diffraction angle after the alpha-Fe2O3 ultrafine particles were decorated.