Interstitial oxide ion conduction in (Ln (2-x) Zrx) Zr2O7+ delta (Ln= Nd, Sm)

Abstract

We have studied the structure and transport properties of (Ln2-xZrx)Zr2O7+x/2 (Ln= Nd, Sm; x=0; 0.2; 0.32; 0.39; 0.48; 0.67; 0.78; 0.96; 1.14; 1.27) solid solutions, which lie in the ZrO2-Ln2Zr2O7 (Ln= Nd, Sm) isomorphous miscibility range (33.3, 29, 26.6, 25.3, 23.5, 20, 18, 15, 12, 10 mol% Ln2O3) in the Nd2O3-ZrO2 (NdZrO) and Sm2O3-ZrO2 (SmZrO) systems. Major attention has been focused on the structure and properties of pyrochlore-like (Ln2 xZrx)Zr2O7+x/2 (Ln=Nd, Sm) solid solutions with x = 0–0.78, which are thought to be potential interstitial oxide ion conductors. The crystal structure of the solid solutions has been investigated by X-ray and neutron diffraction techniques using Rietveld refinement, and their microstructure has been examined by SEM. The excess oxygen content of the (Ln2-xZrx)Zr2O7+x/2 (Ln= Nd, Sm; x=0.2;0.32) pyrochlore-like solid solutions has been determined by thermal analysis and mass spectrometry in a reducing atmosphere (H2/Ar-He). The transport properties of the solid solutions in the two systems have been studied by impedancespectroscopy in air. © International Union of Crystallography