Evolution of the structure with the composition and the defect arrangement in the gadolinium and samarium doped and co-doped ceria systems: A molecular dynamics study

S Vives and D Ramel and C Meunier, SOLID STATE IONICS, 364, 115611 (2021).

DOI: 10.1016/j.ssi.2021.115611

We investigate the evolution of the fluorite structure in the Ce1-xMxO2-x/2 system with Gd and Sm as Rare Earth (RE) doping cations and Gd/Sm as co-doping couple using Molecular Dynamics at 298 K. Doping cations and oxygen vacancies are introduced in the CeO2 fluorite lattice through two different arrangements the Random one and the Neighbour one. The evolution of the lattice parameter is compared with different models and experimental data extracted from the literature. Results concerning the chemical expansion and the oxygen vacancy radius are commented. The calculation of the Radial Distribution Function (RDF) allows to observe two components for the Ce-Ce, Ce-M and M-M (M = Gd, Sm, Gd/Sm) bond length as it is the case in the C-type RE2O3 structure. The percolation concept is introduced and discussed based on the evolution of the M-M group size distribution and the M-O coordination number.

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