Structural, EPR, optical and magnetic properties of α-Fe₂O₃ nanoparticles.

α-Fe(2)O(3) nanoparticles were synthesized by a low temperature solution combustion method. The structural, magnetic and luminescence properties were studied. Powder X-ray diffraction (PXRD) pattern of α-Fe(2)O(3) exhibits pure rhombohedral structure. SEM micrographs reveal the dumbbell shaped particles. The EPR spectrum shows an intense resonance signal at g≈5.61 corresponding to isolated Fe(3+) ions situated in axially distorted sites, whereas the g≈2.30 is due to Fe(3+) ions coupled by exchange interaction. Raman studies show A(1g) (225 cm(-1)) and E(g) (293 and 409 cm(-1)) phonon modes. The absorption at 300 nm results from the ligand to metal charge transfer transitions whereas the 540 nm peak is mainly due to the (6)A(1)+(6)A(1)→(4)T(1)(4 G)+(4)T(1)(4 G) excitation of an Fe(3+)-Fe(3+) pair. A prominent TL glow peak was observed at 140°C at heating rate of 5 °Cs(-1). The trapping parameters namely activation energy (E), frequency factor (s) and order of kinetics (b) were evaluated and discussed.