Covalency, hybridization and valence state effects in nano- and micro-sized ZnFe2O4
- Covalency, hybridization and valence state effects in nano- and micro-sized ZnFe2O4
- 임원철; 채근화; 원성옥; 김소희; Jitendra Pal Singh; Ik-Jae Lee
- Covalency; hybridization and valence state; ZnFe2O4
- Issue Date
- VOL 18, NO 15, 2701-2711
- In the present work, Fe valence state, covalency effects, and metal– oxygen hybridization are discussed for ZnFe2O4 using X-ray absorption spectroscopy. A few sets of nano-sized and micro-sized zinc ferrite were synthesized using the nitrate method. Nanoparticles of ZnFe2O4 were synthesized by heating precursor at 300, 400, 500, 800, 1000, and 1200 °C for 1 h. To synthesize micro-sized ZnFe2O4, the obtained nanoparticles were annealed at 1200 °C for 12 h (bulk treatment). X-ray diffraction shows the presence of cubic spinel phase in nano-sized as well as micro-sized ZnFe2O4. Scanning electron microscopy measurements show that particle size ranges are 40– 80 nm and 1– 2 μm for nano-sized and micro-sized ZnFe2O4, respectively. Fe L-edge spectra of these materials envisage the presence of spectral features corresponding to t2g and eg symmetry states created due to Fe(2p3/2)-Fe(3d) and Fe(2p1/2)-Fe(3d) in octahedral crystal field. This reflects the presence of Fe3+ states in nano-sized and micro-sized ZnFe2O4. eg states dominate in micro-sized ZnFe2O4. O K-edge spectra for these materials can be distinguished by pre-edge and post-edge regions. Pre-edge and post-edge regions are associated with O(2p)– Fe(3d) and O(2p)– Fe(4s,4p) hybridized states. The extent of hybridization estimated from the intensity ratio of O(2p)– Fe(4s,4p) hybridized states is higher in nano-sized ZnFe2O4.
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