From fluorite to pyrochlore: Characterisation of local and average structure of neodymium zirconate, Nd₂Zr₂O₇

The structural characterisation of Nd₂Zr₂O ₇ prepared via a precursor route was performed using a combination of local and average structure probes (neutron total scattering, X-ray and neutron diffraction). We present the first total scattering and reverse Monte Carlo (RMC) modelling study of Nd₂Zr₂O₇, which provides compelling evidence for the adoption of a disordered fluorite-type structure by Nd₂Zr₂O₇ prepared by a low-temperature precursor route. Annealing the material at high temperatures leads to a transformation to a pyrochlore-type structure; however, Rietveld refinement using powder neutron diffraction data shows that the oxygen sublattice retains a degree of disorder.