Electrons of alkali metals in regular nanospaces of zeolites
Electrons of alkali metals in regular nanospaces of zeolites
复制标题
沸石规则纳米空间中碱金属的电子
DOI：
10.1080/23746149.2017.1280415
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
T. Nakano and Y. Nozue
中科院分区：
文献类型：
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作者：
谷中慎太郎;井田和則;岡野智宏;北尾真司;瀬戸誠;金道浩一;小濱芳允;的場正憲;神原陽一;T. Nakano and Y. Nozue
碱金属负载到沸石晶体的规则纳米空间(纳米笼)中的电子表现出新的电子性质，如亚铁磁性、铁磁性、反铁磁性、绝缘体到金属的转变等，这取决于碱金属的种类、负载密度和沸石骨架的结构类型。这些性质与含有自由电子的大块碱金属的性质完全不同。碱金属团簇被稳定在沸石的笼子中，形成了新的s电子量子态，如球形量子阱模型中的1s态、1p态和1D态。电子关联、极化子效应和s-电子量子态的轨道简并对呈现这种新的电子性质起着关键作用。在紧束缚近似的基础上，给出了关联极化子系统的t-U-S-n图，并根据所谓的Holstein-Hubbard哈密顿量给出了关联极化子系统的t-U-S-n图：通过笼子窗口的电子转移能(T)，同一笼子中两电子之间的库仑排斥能(U)，由于阳离子位移而产生的短程电子-声子相互作用能(S)，以及每个笼子的平均s电子数(N)。除了碱金属团簇的胶体背景模型外，在团簇的1p简并轨道上观察到了巨大的自旋-轨道相互作用，类似于Rashba机制。
Thes-electrons of alkali metals loaded into regular nanospaces (nanocages) of zeolite crystals display novel electronic properties, such as a ferrimagnetism, a ferromagnetism, an antiferromagnetism, an insulator-to-metal transition, etc., depending on the kind of alkali metals, their loading density, and the structure type of zeolite frameworks. These properties are entirely different from those in bulk alkali metals of free-electrons. Alkali-metal clusters are stabilized in cages of zeolites, and new quantum states ofs-electrons, such as 1s, 1p, and 1d states in the spherical quantum-well model, are formed. An electron correlation, a polaron effect, and an orbital degeneracy in the quantum states ofs-electrons play critical roles in taking on the novel electronic properties. Electronic properties can be overviewed systematically by a coarse-grained model of localizeds-electron states in cages based on the tight-binding approximation, followed by thet-U-S-ndiagram of the correlated polaron system given by the so-called Holstein–Hubbard Hamiltonian: an electron transfer energy through windows of cages (t), a Coulomb repulsion energy between twos-electrons in the same cage (U), a short-range electron-phonon interaction energy due to the cation displacements (S), and an average number ofs-electrons per cage (n). Beyond the jellium background model of alkali-metal clusters, a huge spin-orbit interaction has been observed in the 1p degenerate orbitals of clusters, similarly to the Rashba mechanism.