Effect of Pr on the electrical and chemical properties of cerium oxide prepared by combustion method

Abstract

Nanoparticles of Ce1−xPrxO2 (X: 0.6 and 0.8), were synthesized by the combustion method using citric acid as chelating and fuel agent. The X‐ray diffraction patterns and Rietveld refinements confirm that samples shown as a single phase in a cubic fluorite structure, with an increase in the lattice parameter as a function of Pr con-centration. The crystallite size domains obtained by the Scherrer formula, confirm values around 10 and 37 nm. The scanning electron microscopy images, show that the solids are composed of dense heterogeneous aggregates. The X‐ray photoelectron spectroscopy, reveals that oxides are composed of cerium and praseodymium cations in oxidation states 4+ and 3+ respectively. The TPR‐H2 profiles indicate that cerium and praseodymium cations present in the obtained systems are completely reduced to Ce3+ and Pr3+ at temperatures above 790°C. The impedance spectroscopy data at room temperature showed that the conduction processes for the two systems take place at the grain boundaries. The Ce0.2Pr0.8O2 system offer lower resistance, due to the high amount of Pr3+ ions inserted in the structure and the high amount of oxygen vacancies formed in the synthesis process.