Fast Na +-ion transport in skeleton structures

Skeleton structures have been explored experimentally for fast Na +-ion transport. A skeleton structure consists of a rigid skeletal array of atoms stabilized by electrons donated by alkali ions partially occupying sites in a three dimensionally linked interstitial space. Fast Na +-ion transport was demonstrated in several structures, and the system Na 1+xZr 2P 3−xSi xO 12 has a Na +-ion resistivity at 300°C of ϱ 300 ≲ 5Ω- cm for x ≈ 2, which is competitive with the best β″-alumina. An activation energy ε a ≈ 0.29 eV is about 0.1 eV larger than that of β″-alumina.