Synthesis and Characterization of Undoped and Co-Doped SnO2 Nanoparticles

Author(s) R.N. Mariammal, N. Rajamanickam, K. Ramachandran
Affiliations School of Physics, Madurai Kamaraj University Madurai – 21, India
Issue Volume 3, Year 2011, Number 1, Part 1
Dates Received 04 February 2011, in final form 18 March 2011, published online 23 March 2011
Citation R.N. Mariammal, N. Rajamanickam, K. Ramachandran, J. Nano- Electron. Phys. 3 No1, 92 (2011)
PACS Number(s) 78.67.Bf, 75.75. + a, 61.72.uf
Key words Nanoparticles (61) , Semiconductors (20) , Scanning electron microscopy (14) , Photoluminescence (15) , Magnetic properties (7) .
Undoped and Co-doped (1 and 3 at. %) SnO2 nanoparticles were synthesized by a simple co-precipitation method. X-Ray diffraction data revealed that both undoped and doped samples crystallize in the tetragonal rutile phase with CoO phase in doped samples. The lattice parameters of doped samples calculated from XRD data do not vary much when compared to undoped one indicating that Co has not substituted the host lattice. The surface morphology investigated by SEM indicates the cluster formation in Co-doped (1 and 3 at. %) nanoparticles and the chemical composition of the samples were analyzed by energy dispersive spectroscopy (EDS). UV-Vis spectrum of undoped system showed absorption at 408 nm (3.04 eV), which is red shifted by 0.56 eV compared to bulk SnO2 (3.6 eV) due to the cluster nature of the sample. The UV-Vis spectra of doped samples showed absorption in the visible region due to the formation of CoO phase, which is also evident from the XRD spectra. PL spectra showed characteristic UV emission at 409 nm and blue emission at 480 nm. The characteristic vibrational modes of SnO2 were studied from FTIR analysis. EPR measurement of Co-doped (3 at .%) SnO2 nanoparticles showed the paramagnetic behavior which may be attributed to the occupation of Co2+ ions in the interstitial site rather than the substitutional site. The absence of ferromagnetism is due to the high doping concentration of Co (> 1 at. %) and also due to the high annealing temperature which destroys the hyperfine splitting.