From Insulator to Electride: A Theoretical Model of Nanoporous Oxide 12CaO·7Al2O3

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• 作者：Peter V. Sushko ; Alexander L. Shluger ; Masahiro Hirano ; Hideo Hosono
• 刊名：Journal of the American Chemical Society
• 出版年：2007
• 出版时间：January 31, 2007
• 年：2007
• 卷：129
• 期：4
• 页码：942 - 951
• 全文大小：324K
• 年卷期：v.129,no.4(January 31, 2007)
• ISSN：1520-5126

文摘

Recently, a novel inorganic electride stable at room temperatures has been obtained by reducinga complex nanoporous oxide 12CaO·7Al₂O₃ (C12A7) in a Ca atmosphere (Matsuishi, S.; Toda, Y.;Miyakawa, M.; Hayashi, K.; Kamiya, T.; Hirano, M.; Tanaka, I.; Hosono, H. Science 2003, 301, 626). Inthis system, up to 2.3 × 10²¹/cm³ electrons can be accommodated in a three-dimensional network of cagesformed by a positively charged oxide framework. We demonstrate theoretically that at all concentrations,n_e, the electrons are neither associated with specific atoms nor fully delocalized. At low n_e, the electronsare isolated from each other and resemble the color centers in insulating materials. They are well localizedin some of the lattice cages and yield strong inhomogeneous lattice distortions that provide polaron-typecage-to-cage electron hopping. As n_e increases, the electrons form a denser electron gas and becomemore evenly spread over all available lattice cages. At sufficiently high n_e, the system becomes metallicbut still retains partially localized character of the conducting electrons. We describe the nature of theelectronic states at the Fermi level and predict the changes in the optical and magnetic properties of thissystem as a function of n_e.