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

In the present study we synthesized conductive nanoscale [Ca 24 Al 28 O 64 ] 4+ (4e - ) (hereafter denoted as C 12 A 7 :e - ) material, and reduced graphene oxide (rGO) was produced, which was unexpected; graphene oxide was removed after melting the sample. The conductivity of C 12 A 7 :e - composites synthesized at 1550 °C was 1.25 S cm -1 , and the electron concentration was 5.5 × 10 19 cm -3 . The estimated BET specific surface area of the highly conductive sample was 20 m 2 g -1 . Pristine C 12 A 7 :e - electride was obtained by melting the composite powder, but the nano size of C 12 A 7 :e - particles could not be preserved; the value of conductivity was ∼28 S cm -1 , electron concentration was ∼1.9 × 10 21 cm -3 , and mass density was 93%. For C 12 A 7- x V x :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 × 10 21 cm -3 ; this enhancement in conductivity was also proposed by a theoretical study but lacked any associated experimental support.