Disordering mechanism in nanocrystalline Gd2(Ti1-xZrx)2O7 materials for nuclear waste disposal: a multiscale diffraction study

The purpose of this proposal is to investigate the structural evolution of Gd2(Ti1-xZrx)2O7 nanoparticles synthesized by a sol-gel approach upon increasing annealing temperature (T). The transition from initial amorphous precursors to nanocrystalline materials with a pyrochlore/fluorite structure that occurs during the annealing procedure can be regarded as the inverse path of the irradiation-induced disordering/amorphization of the crystalline compounds. The proposed experiment will help to elucidate the disordering process that might affect these potential nuclear waste storage materials without using radioactive elements or irradiation sources. The study will be a multiscale investigation of both the local- and long-range structure and will be carried out by means of High-Resolution X-ray Powder Diffraction (HR-XRPD). Data analysis will be performed via the Rietveld method in the reciprocal space and the Pair Distribution Function (PDF) method in the real space.