Cr-Doping-Induced Ferromagnetism in CeO_2-δ Nanopowders

Abstract:

The room-temperature ferromagnetism of Cr-doped cerium oxide (Ce_0.96Cr_0.04O_2δ) nanopowders synthesized using a sol-gel process is reported in this paper. XRD and Raman spectroscopy confirm that the Cr atoms successfully displaced some of the Ce atoms in the CeO₂ lattice without forming any impure phases. The results also confirmed that all calcined samples exhibited a single-phase fluorite structure. The crystallite size (as confirmed by XRD) and the particle size (as confirmed by Raman spectroscopy) increased as the calcination temperature increased. Magnetic measurements indicated that the room-temperature ferromagnetism of the sample was sensitive to the calcination temperature. When the calcination temperature increased, the saturation magnetization decreased while the coercivity increased, which corresponds to less dense and larger particles. The calcined sample at 400°C exhibited superior magnetic properties with the highest saturation magnetization (M_s) of 2.5 × 10^-2 emu/g (H_c ~ 1.27 kOe). The results of the Raman and X-ray photoelectron spectroscopies suggest that the nature of the observed room temperature ferromagnetism in the samples are likely a result of the oxygen vacancies induced by Cr-doping in CeO₂.

• Periodical: Advanced Materials Research (Volume 975)
• Pages: 42-49
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.975.42
• Online since: July 2014
• Authors: Nilson S. Ferreira*, Marcelo Andrade Macedo
• Keywords: Cerium Oxide, Chromium, Ferromagnetism, Nanopowder, Room Temperature

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