Study on the crystal structure of (Gd 2− x Ce x )Ti 2 O 7 (0 ≤ x ≤ 0.8) pyrochlore

Abstract

Synthesis, characterisation and crystal structure analysis studies of oxides in (Gd_2−xCe _x )Ti₂O₇ series have been reported, Ce³⁺ used as a surrogate for Pu³⁺ because they have similar physical and chemical properties. In the present report, a series of pyrochlore-type crystal with composition (Gd_2−xCe _x )Ti₂O₇ (0 ≤ x ≤ 0.8) were successfully synthesised by the solution combustion followed by high temperature calcining. The phase purity and crystal structure of samples were investigated by X-ray diffraction analysis as well as Rietveld refinement. It was observed that the solubility of Ce³⁺ in the lattice of Gd₂Ti₂O₇ pyrochlore is 39.62 mol.-%. The calculated lattice parameters and the simulated XRD patterns of (Gd_2−xCe _x )Ti₂O₇ (x = 0, 0.5, 1) were obtained based on the density functional theory. The results of theoretical calculation are quite consistent with the results of the experiment. Additionally, the grain size and the visual information about the microscopic structure of the (Gd_2−xCe _x )Ti₂O₇ crystals were obtained by transmission electron microscopy.

Keywords

Solution combustion Pyrochlore Crystal structure First-principle calculations Solubility Lattice parameters Rietveld refinement X-ray diffraction analysis

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