  The density functional theory with generalized gradient approximation has
been used to investigate the electronic structure of gadolinium pyrochlore
A2Zr2O7 (A=Gd, Nd) ceramic synthesized in polycrystalline form by solid state
reaction. Structural characterization of the compound was done through X-ray
diffraction (XRD) followed by Rietveld analysis of the XRD pattern. The Zr-K
edge X-ray absorption (XAFS) spectra of A2Zr2O7 (A=Gd, Nd) were analysed
together with those Zr-foil, which was used as reference compounds. X-ray
photoemission spectroscopy (XPS), X-ray absorption near edge structure (XANES)
and extended X-ray absorption fine structure (EXAFS) for A2Zr2O7 (A=Gd, Nd) has
been employed to obtain quantitative structural information on the Zr-local
environment. The band gap is estimated using UV-Vis spectroscopy. The crystal
structure is face centered cubic, space group being Fd-3m (No. 227). The total
energies in this work were calculated using the generalized gradient
approximation to DFT plus on-site repulsion (U) method.
