A novel enhancement of ionic conductivity in the cationdeficient apatite La9.33(SiO4)6O2

Abstract

Al can be doped into the oxide ion conductor La9.33(SiO4)6O2 according to the formula La9.33 + x/3(SiO4)6 − x(AlO4)xO2 where 0 ≤ x ≤ 2; a conductivity enhancement of 1–2 orders of magnitude is observed for intermediate x values and illustrates the important role that La vacancies have in optimising the conductivity.