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

Abstract

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 C₁₂A_7−xV_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 × 10²¹ cm⁻³; this enhancement in conductivity was also proposed by a theoretical study but lacked any associated experimental support.