Aluminothermic synthesis of [Ca24Al28O64]4+(4e−) electride ceramic directly from Ca3Al2O6 precursor

Abstract

Mayenite-derived electride [Ca24Al28O64]4+(4e−) has been successfully synthesized via an aluminothermic reaction of Ca3Al2O6 (C3A), Al2O3, and Al powders at 1070 °C for 10 min using spark plasma sintering (SPS) process in a vacuum. The C3A precursors were directly derived from high temperature calcinating in an ambient atmosphere. The as-synthesized C12A7:e− exhibits an electron density of ∼2.3 × 1021cm−3, a spin concentrations of ∼6.7 × 1019cm−3 and optical absorption bands of 0.5eV and 2.48ev at room temperature. Electronic structure was also evaluated by electron paramagnetic resonance (EPR). The appearance of Dysonian characteristic, a typical feature of good electronic conductors, strongly suggested the formation of conductive mayenite structure. This developed and efficient route not only proposes an modified precursor for the synthesis of high-quality C12A7:e− but also provide more comprehensive insights into mayenite research.