Changes in surface morphology and band gap energy of nanostructured Fe2O3 during high temperature annealing

Abstract

Atomic Force Microscopy (AFM) has been used to study the changes in surface morphology of nanostructured Iron III oxide (Fe₂O₃) during annealing at temperatures of 573, 673, and 733 K for period of 25 hours in each ca-se. The microstructures were examined to determine the bandgap energy, corresponding to values of voltages on the current-voltage (I-V) curve where the current remained zero. Ferritin molecules comprising of a self assembl-ed core of iron oxide were heated to produce nanoparticles embedded in the ferritin shell by Langmuir-Schaefer method. Upon annealing, the nanoparticles clustered preferentially along the boundaries on the substrate which coalesced to increase the cluster sizes and thereby decreased the surface area. The bandgaps measured by AFM after annealing the samples in air for 25 hours increased from 1.55 eV at 573 K to 1.61 eV at 673 K, and to 1.87 eV at 733 K. The study confirmed that in nanoscale region, the particle size and band gap energy varied with annealing temperature.

Keywords: Surface Morphology, Bandgap Energy, Nanostructures, Atomic Force Microscopy, Langmuir-Schaefer Method