Mayenite-based electride C12A7e − : an innovative synthetic method via plasma arc melting

• Published in: Materials chemistry frontiers Vol. 5; no. 3; pp. 1301 - 1314
• Main Authors: Weber, Sebastian, Schäfer, Sebastian, Saccoccio, Mattia, Seidel, Karsten, Kohlmann, Holger, Gläser, Roger, Schunk, Stephan A.
• Format: Journal Article
• Language: English
• Published: London Royal Society of Chemistry 11.02.2021
• Subjects: Aluminum; Electric arc melting; Graphite; Oxidation; Plasma; Plasma arc melting; Reducing agents; Synthesis
• ISSN: 2052-1537; 2052-1537
• DOI: 10.1039/D0QM00688B

Mayenite-based electrides have been reported as promising support materials for applications in heterogeneous catalysis. However, the current synthetic access to mayenite materials is limited by a method portfolio of complex procedures far from industrial applicability and thus hinders research and application in a broader context. We report the first plasma-based synthesis of the mayenite-based electride [Ca 24 Al 28 O 64 ] 4+ :(4e − ) obtained by plasma treatment of oxygen-mayenite solid-reductant precursor mixtures. Aluminum and graphite can be successfully used as solid reductant: while aluminum leads to enhanced secondary phase formation of krotite during the treatment, the use of graphite as solid reductant, leads to phase-pure samples. We further critically discuss challenges and limitations in applying literature reported methods to quantitatively determine the electron concentration of the electrides. For this purpose, EPR-, DRUV/vis-spectroscopy, Rietveld refinement of PXRD and DSC-TG analysis under oxidizing atmosphere were applied and critically revised. We show the possibilities using the facile plasma-based synthesis as a scalable method to obtain semiconducting and close to metallic conducting electrides.