Heavily doped oxygen-ion conducting Ln2+xTi2-xO7-δ-(Ln=Ho-Lu; x=0.44-0.81) pyrochlores: Crystal structure, microstructure and electrical conductivity

摘要

There are at least two conductivity maxima in the Ln2O3-TiO2 (Ln=Ho-Lu) systems. High oxide-ion conductivity is typically offered by stoichiometric or near-stoichiometric Ln2+xTi2-xO7-δ (Ln=Ho-Lu; x=0-0.096) pyrochlores and heavily doped, disordered Ho2+xTi2-xO7-δ (0.48 ≤ x ≤ 0.67) pyrochlores just near the boundary of the continuous P→F phase transition. The conductivity of the fluorite-like Ln2+xTi2-xO7-δ (Ln=Er-Lu; 0.63-0.74) solid solutions is lower than that of the Ln2+xTi2-xO7-δ (Ln=Er-Lu; x=0-0.096) pyrochlores, similar to what was reported for the Y2O3-TiO2 system.