Preferences help
enabled [disable] Abstract
Number of results
2014 | 125 | 3 | 756-759
Article title

Eu-Doped Cerium Oxide Nanoparticles Studied by Positron Annihilation

Title variants
Languages of publication
The defect characteristics of cerium oxide (CeO_2) nanoparticles prepared through a solvothermal process and doped by europium to different concentrations ([Eu] = 0, 0.1, 0.5, 1, ..., 50 wt%) were studied by positron lifetime and coincidence Doppler broadening measurements. The particle sizes estimated from X-ray diffraction showed a reducing trend with increasing doping concentration except an increase during [Eu] = 0.1-1 wt%. The latter effect is attributed to the reduction of Ce^{4+} ions to Ce^{3+} resulting into the release of vacancies and formation of Ce^{3+}-vacancy associates. The lattice parameter increased with the decrease in particle size. Quantum confinement effects were observed in optical absorption studies as increase of band gap in particles of sizes below 7-8 nm. The vacancy-type defects were investigated by positrons. A lifetime of 176 ± 4 ps less than 187-189 ps reported for positrons in bulk CeO_2 reveals trapping of positrons in vacancy-type defects within the nanocrystallites. The defect-specific positron lifetime is admixed with that at the crystallite surfaces and it increased due to vacancy agglomeration at higher doping concentrations. Coincidence Doppler broadening studies indicated positron annihilation in defects surrounded by oxygen ions and the S-W plot showed the effect of quantum confinement through a peak-like kink or shoulder in the plot. Optical absorption studies have supported this observation.
Physical description
  • [1] L. Chen, P. Fleming, V. Morris, J.D. Holmes, M.A. Morris, J. Phys. Chem. C 114, 12909 (2010), doi:10.1021/jp1031465
  • [2] S. Tsunekawa, J.-T. Wang, Y. Kawazoe, J. Alloys Comp. 408-412, 1145 (2006), doi:10.1016/j.jallcom.2004.12.140
  • [3] P.M.G. Nambissan, in: Nanotechnology: Synthesis and Characterization, Vol. 2, Eds. Shishir Sinha, N.K. Navani, J.N. Govil, Studium Press LLC, Houston 2013, p. 455
  • [4] P.M.G. Nambissan, J. Phys., Conf. Series 443, 012040 (2013), doi:10.1088/1742-6596/443/1/012040
  • [5] J.V. Olsen, P. Kirkegaard, N.J. Pedersen, M. Eldrup, Phys. Status Solidi C 4, 4004 (2007), doi:10.1002/pssc.200675868
  • [6] A. Chatterjee, K. Ramachandran, A. Kumar, A. Behere, Linux Advanced Multi Parameter System (2013)
  • [7] A.L. Patterson, Phys. Rev. 56, 978 (1939), doi:10.1103/PhysRev.56.978
  • [8] A.V. Thorat, T. Ghoshal, J. Holmes, P.M.G. Nambissan, M.A. Morris, Nanoscale 6, 608 (2014), doi:10.1039/c3nr03936f
  • [9] S.J. Chang, M. Li, Q. Hua, L.J. Zhang, Y.S. Ma, B.J. Ye, W.X. Huang, J. Catalysis 293, 195 (2012), doi:10.1016/j.jcat.2012.06.025
  • [10] A. Sachdeva, S.V. Chavan, A. Goswami, A.K. Tyagi, P.K. Pujari, J. Solid State Chem. 178, 2062 (2005), doi:10.1016/j.jssc.2005.04.016
  • [11] A. Uedono, K. Shimoyama, M. Kiyohara, K. Yamabe, J. Appl. Phys. 94, 5193 (2003), doi:10.1063/1.1606112
  • [12] S. Deshpande, S. Patil, S.V.N.T. Kuchibhatla, S. Seal, Appl. Phys. Lett. 87, 133113 (2005), doi:10.1063/1.2061873
Document Type
Publication order reference
YADDA identifier
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.