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

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 - delta (Ln = Ho-Lu; x = 0-0.096) pyrochlores and heavily doped, disordered Ho2 + xTi2 - xO7 - delta (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 - delta (Ln = Er-Lu; 0.63-0.74) solid solutions is lower than that of the Ln2 + xTi2 - xO7 - delta (Ln = Er-Lu; x = 0-0.096) pyrochlores, similar to what was reported for the Y2O3-TiO2 system.