Structural modifications of nanostructured ceria CeO₂,xH₂O during dehydration process

• Published in: Powder technology 2012, Vol.215, p.66-71
• Main Authors: Bourja, L, Bakiz, B, Benlhachemi, A, Ezahri, M, Villain, S, Favotto, C, Valmalette, J.-C, Gavarri, J.R
• Format: Article
• Language: English
• Subjects: cerium; Crystallites; Dehydration; Diffraction; Nanocomposites; Nanomaterials; Nanostructure; oxygen; Raman spectroscopy; scanning electron microscopy; Surface water; temperature; thermal degradation; thermogravimetry; X-ray diffraction; X-rays
• ISSN: 0032-5910; 1873-328X
• DOI: 10.1016/j.powtec.2011.09.008

Hydrated nanostructured cerium dioxide CeO₂, xH₂O (hydrated nanoceria) has been synthesized in room conditions via a precipitation route. This hydrated nanoceria phase has been subjected to thermal decomposition in the temperature range from 25°C to 800°C. At least three decomposition steps have been observed in thermal and thermogravimetric analyses. Three different samples of cubic nanoceria respectively obtained at room temperature (RT-nanoceria), 80°C (80-nanoceria) and 600°C (600-nanoceria) have been studied by X-Ray diffraction, Raman spectroscopy and scanning electron microscopy analyses. The analyses of X-ray diffraction profiles and Raman vibrational bands have clearly shown that dehydration is accompanied by increasing crystallite size, lattice parameter contraction. The cubic structure of hydrated RT-nanoceria might be associated with a complex chemical formula unit involving Ce⁴⁺, Ce³⁺ mixed valences, oxygen vacancies, lattice and surface water and OH⁻ proton species.