Thin film and bulk fabrication of room-temperature-stable electride C12A7 : e(-) utilizing reduced amorphous 12CaO center dot 7Al(2)O(3)(C12A7)

摘要

Heavily electron-doped 12CaO center dot 7Al(2)O(3)(C12A7) exhibits unique electronic properties such as high electronic conductivity of 1500 S cm(-1) (to superconductor via metal-insulator transition) and a very small work function (2.4 eV) arising from electrons entrapped in sub-nanometer-sized cages inherent to the crystal structure. We report the efficient synthetic processes of bulk and thin film C12A7:e(-) using the reduced C12A7 melt or a-C12A7. Solidification of the melt produced in carbon crucibles and crystallization of the reduced C12A7 glass (insulating) in vacuum yielded bulk C12A7:e(-). It was suggested that C-2(2-) ions work as a template to form the nano-cages in the crystallization processes. The films of C12A7:e(-) were fabricated by the reduction treatment of crystalline C12A7 thin films with reduced a-C12A7. By applying this process, heavily electron-doped thin films of 12SrO center dot 7Al(2)O(3) with the same crystal structure as C12A7 but a non-equilibrium phase was first realized.