Tuning the electronic properties of C12A7 via Sn doping and encapsulation
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Tuning the electronic properties of C12A7 via Sn doping and encapsulation Navaratnarajah Kuganathan1,2,* 1 2
and Alexander Chroneos1,2,*
Department of Materials, Imperial College London, London SW7 2AZ, UK Faculty of Engineering, Environment and Computing, Coventry University, Priory Street, Coventry CV1 5FB, UK
Received: 9 June 2020
ABSTRACT
Accepted: 8 October 2020
Cation doping in electride materials has been recently considered as a viable engineering strategy to enhance the electron concentration. Here we apply density functional theory-based energy minimisation techniques to investigate the thermodynamical stability and the electronic structures of Sn-doped and Snencapsulated in stoichiometric and electride forms of C12A7. The present calculations reveal that encapsulation is exoergic and doping is endoergic. The electride form is more energetically favourable than the stoichiometric form for both encapsulation and doping. Encapsulation in the electride results a significant electron transfer (1.52 |e|) from the cages consisting of extra-framework electrons to the Sn atom. The Sn forms almost ? 4 state in the doped configuration in the stoichiometric form as reported for the electride form in the experiment. Similar charge state for the Sn is expected for the electride form though the extra-framework electrons localised on the Sn. Resultant complexes of both forms are magnetic. Whilst significant Fermi energy shift is noted for the doping in C12A7:O2- (by 1.60 eV) towards the conduction band, there is a very small shift (0.04 eV) is observed in C12A7:e-. Future experimental study on the encapsulation of Sn in both forms of C12A7 and doping of Sn in the stoichiometric form can use this information to interpret their experimental data.
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The Author(s) 2020
1 Introduction Rapid advancement of the electronic technologies necessitates the development of novel functional materials with cheap, non-hazardous, electronically conductive and tunable characteristics for the enhancement of electronic properties. In recent years, there has been a growing interest in inorganic electride materials because of their promising
applications in electronics due to their low work function and good electronic conductivity [1–7]. As there are chemically independent electrons occupied in electrides, it is expected that they can be used as electron emitters, superconductors and catalysts for different reactions including depletion of CO2 and activation of N2 [8–12]. Various stable inorganic electrides such as C12A7 [1, 13] and Ca2N [14] have been reported in the literature. Based on the nature of
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https://doi.org/10.1007/s10854-020-04633-8
J Mater Sci: Mater Electron
electron localisation they are classified as zero-dimensional (electrons localising in cavities) [15], onedimensional (electrons localising in a channel) [16] and two-dimensional (electrons confining in a layer) [17]. Due to the potential uses of electrides in solidstate phys
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