Facile metal-free reduction-based synthesis of pristine and cation-doped conductive mayenite

In the present study we synthesized conductive nanoscale [Ca24Al28O64]4+(4e−) (hereafter denoted as C12A7:e−) material, and reduced graphene oxide (rGO) was produced, which was unexpected; graphene oxide was removed after melting the sample. The conductivity of C12A7:e− composites synthesized at 1550 °C was 1.25 S cm−1, and the electron concentration was 5.5 × 1019 cm−3. The estimated BET specific surface area of the highly conductive sample was 20 m2 g−1. Pristine C12A7:e− electride was obtained by melting the composite powder, but the nano size of C12A7:e− particles could not be preserved; the value of conductivity was ∼28 S cm−1, electron concentration was ∼1.9 × 1021 cm−3, and mass density was 93%. For C12A7−xVx:e−, where x = 0.25 to 1, the conductivity improved to a maximum value of 40 S cm−1, and the electron density improved to ∼2.2 × 1021 cm−3; this enhancement in conductivity was also proposed by a theoretical study but lacked any associated experimental support.