Study of Fabricating α-Fe₂O₃ Ultrafine Particles by Langmuir-Blodgett Film Technology

The α-Fe₂O₃ ultrafine particles were dispersed in the solutions of stearic acid/n-hexand/chloroform by the ultrasonic method,and fabricated by the Langmuir-Blodgett film technology.They were investigated by mearsof π-A isotherms,UV-visible absorption,IR spectrum,Small-angle X-ray diffraction,TEM and electron diffraction.The results showed:The single molecular area of α-Fe₂O₃ ultrafine partiches/stearic acid composite monolager is bigger than that of stearic acid.It is found that the absorption band edges of α-Fe₂O₃ ultrafine particles modificated by stearic acid significantly shift to the red,which is in contrast with that of bulk Fe₂O₃.This is caused by the influence of dielectric confinement effect.There are two grades Brag-peak appeared in the small-angle X-ray diffraction spectra indicated that the α-Fe₂O₃ ultrafine particles/stearic acid composite film had lamellar-structure.The littler orientation can be induced when there are lattic matching relations between stearic acid monolager and α-Fe₂O₃ ultrafine particles.