TY - JOUR
T1 - Magnetically addressable fluorescent Fe3O4/ZnO nanocomposites
T2 - Structural, optical and magnetization studies
AU - Roychowdhury, A.
AU - Pati, S. P.
AU - Mishra, A. K.
AU - Kumar, S.
AU - Das, D.
PY - 2013/6
Y1 - 2013/6
N2 - Fe3O4/ZnO nanocomposites (NCs) are prepared by a wet chemical route. X-ray diffraction, transmission electron microscopy and Fourier transform infrared spectroscopy studies confirm the coexistence of Fe 3O4 and ZnO phases in the NCs. The UV-vis absorption spectra show a red shift of the absorption peak with increase in Fe 3O4 content indicating a modification of the band structure of ZnO in the NCs. Photoluminescence emission spectra of the NCs display strong excitonic emission in the UV region along with weak emission bands in the visible range caused by electronic transitions involving defect-related energy levels in the band gap of ZnO. Positron annihilation lifetimes indicate that cation vacancies in the ZnO structure are the strong traps for positrons and the overall defect concentration in the NCs decreases with increase in Fe3O4 content. Dc magnetization measurements reveal an anomalous temperature dependence of the coercivity of the NCs that is argued to be due to the anomalous variation of magnetocrystalline anisotropy at lower temperature. The irreversibility observed in the temperature dependent ZFC-FC magnetization points to the presence of a spin-glass phase in the NCs.
AB - Fe3O4/ZnO nanocomposites (NCs) are prepared by a wet chemical route. X-ray diffraction, transmission electron microscopy and Fourier transform infrared spectroscopy studies confirm the coexistence of Fe 3O4 and ZnO phases in the NCs. The UV-vis absorption spectra show a red shift of the absorption peak with increase in Fe 3O4 content indicating a modification of the band structure of ZnO in the NCs. Photoluminescence emission spectra of the NCs display strong excitonic emission in the UV region along with weak emission bands in the visible range caused by electronic transitions involving defect-related energy levels in the band gap of ZnO. Positron annihilation lifetimes indicate that cation vacancies in the ZnO structure are the strong traps for positrons and the overall defect concentration in the NCs decreases with increase in Fe3O4 content. Dc magnetization measurements reveal an anomalous temperature dependence of the coercivity of the NCs that is argued to be due to the anomalous variation of magnetocrystalline anisotropy at lower temperature. The irreversibility observed in the temperature dependent ZFC-FC magnetization points to the presence of a spin-glass phase in the NCs.
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U2 - 10.1016/j.jpcs.2013.01.012
DO - 10.1016/j.jpcs.2013.01.012
M3 - Article
AN - SCOPUS:84875221743
VL - 74
SP - 811
EP - 818
JO - Journal of Physics and Chemistry of Solids
JF - Journal of Physics and Chemistry of Solids
SN - 0022-3697
IS - 6
ER -