One-Step Synthesis of a 12CaO[middle dot]7Al2O3 Electride via the Spark Plasma Sintering (SPS) Method

Abstract

Polycrystalline C12A7 electrides were successfully synthesized via spark plasma sintering (SPS) process. C22− ions, generated from graphite by the spark plasma, presumably serve as a template for the formation of the C12A7 phase during the re-crystallization process and are spontaneously released from the cage of C12A7 during the SPS process, remaining mobile electrons in the cage. The polycrystalline C12A7 electride processed at 1100°C exhibits an electrical resistivity of 1.7 × 10−1 Ω·cm−1, an electron concentration of 5.3 × 1019/cm3 and optical absorptions of 0.4 eV and 2.7 eV at room temperature.