Structure and radiation response of anion excess bixbyite Gd2Ce2O7

The crystal structure analysis of Formula Presented reveals that it crystallizes in a bixbyite-type symmetry (Formula Presented). Analysis of the structure suggests a randomly occupied cation sublattice with infinite correlation length associated with long-range ordered anion sublattice with half of the vacant sites of an ideal bixbyite filled, hence the name anion-excess bixbyite. Ion irradiation experiments and quantitative x-ray diffraction analysis were used to study the separate response of the anion sublattice to swift heavy ion radiation. Analysis of anion and cation correlation lengths as a function of fluence shows that the topological disorder on the anion sublattice grows faster than that on the cation sublattice. The microstructural response at increasing radiation fluences leads to a decrease of the strain after an initial increase, while the variance of the strain increases following the increase of the microdomain wall density. This particular behavior seems responsible for the exceptional radiation resistance of this system that does not display any significant amorphization, even at the highest fluence