Short- and long-range order balance in nanocrystalline Gd2Zr2O7 powders with a fluorite-pyrochlore structure

Abstract

A series of nanocrystalline Gd2Zr2O7 powders has been studied using a combination of X-ray diffraction and X-ray spectroscopy with synchrotron radiation. It has been shown that isothermal annealing of an X-ray amorphous mixed hydroxide first leads to the formation of an oxide nanomaterial with a defect fluorite structure and clearly pronounced nonequivalence of the local environment of the Gd3+ and Zr4+ ions. Increasing heat treatment temperature results in initiation and growth of nanodomains with pyrochlore-type superstructure ordering of cations inside bulkier crystallites of defect fluorite. To adequately describe the evolution of the real nanocrystalline structure of gadolinium zirconate, a combination of X-ray structural methods sensitive to the averaged crystal structure and local atomic structure should be used.