Sol–Gel Synthesis of Tunable Cerium Titanate Materials

Abstract

Cerium titanate structures present a high technological interest because of their optical and catalytic properties. This work reports the synthesis of these materials by a sol–gel methodology that allows mixed oxides with TiIV/CeIII, TiIV/CeIV or TiIV/CeIII–CeIV species to be obtained. Crystallization of CeO2–TiO2 mixed oxides and Ce2Ti2O7 pyrochlore phase was corroborated by XRD and Raman spectroscopy. Magnetic and EPR measurements were performed in order to clarify the oxidation state of the cerium ions in the system as a result of the easy oxidation of CeIII. The firing atmosphere is crucial for the CeIII/CeIV ratio, which is responsible for the different structure, but it also affects the colouration (yellow, green, brown). This methodology offers the possibility to modulate the Ce3+/Ce4+ content and particle sizes providing more ecological coloured pigments based on rare earth elements that could be interesting materials for advanced applications in catalysis.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

The solubility of cerium in La2Ti2O7 by DFT + U calculations

“…For the pure end member, La 2 Ti 2 O 7 pyrochlore has been investigated by Zhang et al [19] and Xiao et al [24], Pruneda et al [43], and Chartier et al [44]. Furthermore, the Ce 2 Ti 2 O 7 pyrochlore structure has also M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 4 been obtained by sol-gel methodology under reductive atmosphere by Mónica Martos et al [57]. In a sense, this research will provide guidance for further researches in experiments.…”

“…A number of studies have been carried out to study the charge state of Ce (or Pu) in pyrochlores doped with Ce (or Pu) [33,[51][52][53] [57] also suggested that the reduction state of cerium ions exist in Ce 2 Ti 2 O 7 pyrochlore. As the classical model of an ionic material with nominal charges is oversimplified, the charge state is not the nominal +3 |e|.…”

Role of surfactants on metal mediated cerium(IV) oxidation of valeraldehyde at room temperature and pressure

“…In the case of cerium, 4f-5d bands of Ce 3+ ions and the CT bands of Ce 4+ ions appear in the same wavelength range ( Fig. 2a-h), which cause them to overlap each other [34,35]. The scanned absorption spectra of the different set of reaction mixtures were taken for both in presence and absence of surfactant and metal ion catalyst Ir(III)/Ru(III) (Fig.…”

Novel magnetic core–shell Ce–Ti@Fe3O4 nanoparticles as an adsorbent for water contaminants removal

“…As shown, two peaks were observed at 250 and 310 nm respectively, which could be attributed to the presence of either Ce(III) or both Ce(III) and Ce(IV) in the nanomaterial. 20,22,23 The slightly shi of the wavelength comparing to the literature could be attributed to the lower temperature of the synthesis of the materials and to the presence of magnetite NPs in the core. Thus, luminescence spectroscopy is necessary to obtain information about the valence of the cerium.…”

“…As reported, the cerium ion in the cerium titanate, Ce 2/3 TiO 3 , is mainly Ce(III). 20 Therefore, because of the overlapping of both bands, it is difficult to determine the species responsible of colour with the colorimetric technique. S1 (ESI 2.5 †) shows the absorption UV-vis spectra of the Ce-Ti@Fe 3 O 4 nanomaterial.…”