title: Structural, EPR, optical and magnetic properties of α-Fe₂O₃ nanoparticles.
abstract: 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.
authors.affiliation: Department of Chemistry, Ambedkar Institute of Technology, Bangalore 560 056, India.
authors.forename: A A
authors.initials: AA
authors.lastname: Jahagirdar
authors.forename: N
authors.initials: N
authors.lastname: Dhananjaya
authors.forename: D L
authors.initials: DL
authors.lastname: Monika
authors.forename: C R
authors.initials: CR
authors.lastname: Kesavulu
authors.forename: H
authors.initials: H
authors.lastname: Nagabhushana
authors.forename: S C
authors.initials: SC
authors.lastname: Sharma
authors.forename: B M
authors.initials: BM
authors.lastname: Nagabhushana
authors.forename: C
authors.initials: C
authors.lastname: Shivakumara
authors.forename: J L
authors.initials: JL
authors.lastname: Rao
authors.forename: R P S
authors.initials: RP
authors.lastname: Chakradhar
mesh_terms: D004578:Electron Spin Resonance Spectroscopy; D005290:Ferric Compounds / Q000737:chemistry*; D007700:Kinetics; D008163:Luminescent Measurements; D060328:Magnetic Phenomena; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D055620:Optical Phenomena; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D005290:Ferric Compounds; C000499:ferric oxide