From insulator to electride: a theoretical model of nanoporous oxide 12CaO.7Al2O3.
From insulator to electride: a theoretical model of nanoporous oxide 12CaO.7Al2O3.
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DOI：
10.1021/ja066177w
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发表时间：
2007-01
影响因子：
15
通讯作者：
P. Sushko;A. Shluger;M. Hirano;H. Hosono
中科院分区：
文献类型：
--
作者：
P. Sushko;A. Shluger;M. Hirano;H. Hosono
最近，通过还原复合纳米多孔氧化物12CaO，获得了一种室温稳定的新型无机电极。7Al2O3 （C12A7）在Ca大气中的应用（Matsuishi， S.; Toda， Y.; Miyakawa， M.; Hayashi， K.; Kamiya， T.; Hirano， M.; Tanaka， I.；细野，H. Science 2003, 301,626）。在该系统中，高达2.3 x 1021/cm3的电子可以被容纳在由带正电的氧化物框架形成的三维笼状网络中。我们从理论上证明，在所有浓度下，电子既不与特定原子相关联，也不完全离域。在低能级，电子彼此隔离，类似于绝缘材料中的色心。它们在一些晶格笼中很好地定位，并产生强烈的非均匀晶格畸变，从而提供极化子型笼间电子跳变。随着ne的增加，电子形成密度更大的电子气体，并更加均匀地分布在所有可用的晶格笼中。在足够高的ne时，体系变成金属，但仍保留部分导电电子的局域特征。我们描述了费米能级上电子态的性质，并预测了该系统的光学和磁性能随ne的变化。
Recently, a novel inorganic electride stable at room temperatures has been obtained by reducing a 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). In this system, up to 2.3 x 1021/cm3 electrons can be accommodated in a three-dimensional network of cages formed by a positively charged oxide framework. We demonstrate theoretically that at all concentrations, ne, the electrons are neither associated with specific atoms nor fully delocalized. At low ne, the electrons are isolated from each other and resemble the color centers in insulating materials. They are well localized in some of the lattice cages and yield strong inhomogeneous lattice distortions that provide polaron-type cage-to-cage electron hopping. As ne increases, the electrons form a denser electron gas and become more evenly spread over all available lattice cages. At sufficiently high ne, the system becomes metallic but still retains partially localized character of the conducting electrons. We describe the nature of the electronic states at the Fermi level and predict the changes in the optical and magnetic properties of this system as a function of ne.