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Facile synthesis of a cationic-doped [Ca24Al28O64]4+(4e) composite via a rapid citrate sol–gel method

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Abstract

One of the greatest challenges in the enhancement of the electrical properties of conductive mayenite [Ca24Al28O64]4+(4e) (hereinafter C12A7:e) is the design of a more suitable/simple synthesis strategy that can be employed to obtain the required properties such as excellent stable electrical conductivity, a high electron concentration, outstanding mobility, and an exceptionally large surface area. Therefore, to synthesize C12A7:e in the metallic state, we proposed a facile, direct synthesis strategy based on an optimized sol–gel combustion method under a nitrogen gas environment using the low-cost precursors Ca(NO3)2·4H2O and Al(NO3)3·9H2O. Using this developed strategy, we successfully synthesized moderately conductive nanoscale C12A7:e powder, but with unexpected carbon components (reduced graphene oxide (rGO) and/or graphene oxide (GO)). The synthesized C12A7:e composite at room temperature has an electrical conductivity of about 21 S cm−1, a high electron concentration of approximately 1.5 × 1021 cm−3, and a maximum specific surface area of 265 m2 g−1. Probably, the synthesized rGO was coated on nanocage C12A7:e particles. In general, the C12A7:e electride is sensitive to the environment (especially to oxygen and moisture) and protected by an rGO coating on C12A7:e particles, which also enhances the mobility and keeps the conductivity of C12A7:e electride stable over a long period. Doped mayenite electride exhibits a conductivity that is strongly dependent on the substitution level. The conductivity of gallium-doped mayenite electride increases with the doping level and has a maximum value of 270 S cm−1, which for the first time has been reported for the stable C12A7:e electride. In the case of Si-substituted calcium aluminate, the conductivity has a maximum value of 222 S cm−1 at room temperature.

Graphical abstract: Facile synthesis of a cationic-doped [Ca24Al28O64]4+(4e−) composite via a rapid citrate sol–gel method

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Publication details

The article was received on 02 Dec 2017, accepted on 26 Jan 2018 and first published on 26 Jan 2018


Article type: Paper
DOI: 10.1039/C7DT04543C
Citation: Dalton Trans., 2018, Advance Article
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    Facile synthesis of a cationic-doped [Ca24Al28O64]4+(4e) composite via a rapid citrate sol–gel method

    K. Khan, A. Khan Tareen, S. Elshahat, A. Yadav, U. Khan, M. Yang, L. Bibbò and Z. Ouyang, Dalton Trans., 2018, Advance Article , DOI: 10.1039/C7DT04543C

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