Physical Properties of ZnCoO Tetrapods and Nanofibers
K. Gasa, K. Fronca, P. Dziawaa, W. Knoffa, T. Wojciechowskia, W. Zaleszczyka, A. Baranowska Korczyca, J.F. Morhangeb, W. Paszkowicza, D. Elbauma, G. Karczewskia, T. Wojtowicza and W. Szuszkiewicza
a Institute of Physics, Polish Academy of Sciences, al. Lotników 32/46, 02-668 Warszawa, Poland
b Institut des Nanosciences de Paris, UMR 7588, UMPC, 140 rue de Lourmel, 75015 Paris, France
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In this paper the physical properties of two types of Co doped ZnO nanostructures: tetrapods and nanofibers grown by a rapid thermal evaporation process and prepared by the electrospinning technique, respectively, were investigated and analyzed. Surface morphology of the samples was examined using scanning electron microscopy. X-ray diffraction measurements showed hexagonal wurtzite crystal structure of both types of investigated nanostructures. Both X-ray diffraction and Raman scattering data confirmed high phase purity of the samples. The magnetic properties studied with the use of the SQUID magnetometer confirmed a presence of ferromagnetic order in analyzed nanostructures. The observed photoluminescence spectra exhibited two groups of lines. The first one, in the ultraviolet spectral range, is due to the optical transitions close to ZnO band gap, the second one in the red region is most probably related to the Co2+ d-d internal transitions. The influence of native defects on the optical properties is also shown and discussed. All results reported here lead us to the conclusion that in the mixed crystal nanostructures obtained, a fraction of the Zn2+ ions is substituted by Co2+ ions.
DOI: 10.12693/APhysPolA.116.868
PACS numbers: 78.55.Et, 78.67.Bf, 81.05.Dz, 81.07.Bc