Structural transition in rare earth doped zirconium oxide: A positron annihilation study

A series of compounds with the general composition Sm2−xDyxZr2O7 (where 0 ≤ x ≥ 2.0) were synthesized by chemical route and characterized by powder X-ray diffraction (XRD) analysis. The rare earth ion namely Sm+3 in the compound was gradually replaced with another smaller and heavier ion, Dy+3 of the 4f series, there by resulting in order–disorder structural transition, which has been studied by positron annihilation lifetime and Doppler broadening spectroscopy. This study reveals the subtle electronic micro environmental changes in the pyrochlore lattice (prevalent due to the oxygen vacancy in anti-site defect structure of the compound) toward its transformation to defect fluorite structure as found in Dy2Zr2O7. A comparison of the changes perceived with PAS as compared to XRD analysis is critically assayed.

Graphical abstractNew microstructural analysis and phase transition of rare earth doped mixed oxide compounds such as: Sm2−xDyxZr2O7 (where x = 0.0 ≤ x ≥ 2.0) that are potentially useful as solid oxide fuels, ionic conductors, optoelectronic materials and most importantly as radiation resistant host for high level rad-waste disposal, structural transition in the system is reported through positron annihilation spectroscopy as there is an indication in the X-ray diffraction analysis.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Zirconium oxide material doped with rare earth ions. ► The method of positron annihilation spectroscopy suggests a phase transition in the system. ► The crystal structure transformation from pure pyrochlore to defect fluorite type of structure is shown by X-ray diffraction results.