Structural and optical properties of sol-gel derived α-Fe2O3 nanoparticles

Abstract

α-Fe2O3 nanoparticles of crystallite size between 3.9 and 9.5nm were synthesized by a simple sol-gel method using iron (III) nitrate nonahydrate (Fe(NO3)3·9H2O) as a precursor. Polyvinyl alcohol (PVA) was added as a capping agent to avoid agglomeration of the nanoparticles. A single pure phase was obtained when the sample was annealed at 300°C and 600°C. The purity was further confirmed with the Fourier Transform Infrared Spectroscopy. The energy band gap of the materials was extrapolated from the Kubelka-Munk relation and it ranges between 1.8 and 2.3eV. The Photoluminescence of the 3 samples shows a broad emission spectrum centered at about 422nm when excited by a 336nm lamp. The emission peaks intensities increased with an increase in the annealing temperature, accept for the 576nm peak, which was quenched as the temperature increased from 300°C to 600°C. The thermoluminescence glow curves were carried out at different heating rates and the samples were exposed to different beta particle doses (82–1315Gy). The activation energy of the trapped electrons was determined.