Structural Characteristics of Cerium Oxide Nanocrystals Prepared by the Microemulsion Method

Abstract

The aim of this work is to investigate the microstructure development of cerium oxide nanocrystal, prepared by the microemulsion process, as a function of annealing temperature in air. Combined with the HRTEM and the thermogravimetric−differential thermal analysis (TG−DTA), the XRD patterns reveal that the sample annealed at 623 K is amorphous, and the formation of cerium oxide nanocrystal occurs above 773 K. The local structural and electronic properties in the nanocrystallization process are probed by X-ray absorption spectra (XAS) at the Ce L3 edge. It is found that the phase structure changes from triclinic to cubic (CeO2), and the electronic structure changes from Ce3+ to Ce4+ upon increasing the annealing temperature.

Structural characteristics of quantum-size ceria nano particles synthesized via simple ammonia precipitation

“…Hence concentration of two oxidation states in the oxide sample can be obtained by the expression given below [39]. The calculations led to the fact that in these ceria nano particles, 67% of cerium is present in the tetravalent state, while the remaining 33% exist as trivalent ion.…”

Structure and properties of cerium oxides in bulk and nanoparticulate forms

“…What may be surprising, is that different preparation techniques lead to observation of widely varied NP size-lattice parameter relationships [20], [38], [39], [40], [41], [42]. All publications report the most noticeable deviation of unit cell parameter value Δa from that one for the bulk (0.5409 nm) can be observed for particles with diameter D < 5 nm.…”

Electrical properties and reactivity under air–CO flows of composite systems based on ceria coated carbon nanotubes

“…Then, as a second step, a composite synthesis was performed. The carbon nanotubes (variable amounts of DWNTs) were first refluxed in a 30% nitric acid solution at 140 • C for 24 h. The as treated DWNTs were dispersed in 50 mg/ml Ce(NO 3 ) 3 solutions, in ultrasonic bath at room temperature, for 1 h. Under heavy stirring, the pH of solutions were controlled and adjusted close to pH 9, by slowly adding NaOH solution. After rinsing with deionised water and drying at 80 • C, the final composite samples were obtained.…”

“…Ceria was investigated as ionic conductor, electronic promoter of heterogeneous catalytic reactions, oxygen storage capacitor in industrial catalytic processes such as automotive exhaust emission control [3][4][5].…”