Structure and Electronic Properties of Potassium-Loaded Zeolite L

Anderson, Paul A.; Armstrong, A. Robert; Porch, Adrian; Edwards, Peter P.; Woodall, LJ

doi:10.1021/jp971737m

Cited by 32 publications

(23 citation statements)

References 27 publications

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“…The expectation value of the SOI in 1p orthogonalized s-electron wave functions of 1 √ 2 φ x ± iφ y is given by φ x | H SO φ y which consists of three terms: (1) the cluster orbital term u x | H SO u y , (2) the cluster orbital vs. ion core term u x | H SO ϕ y and (3) the ion core term ϕ x | H SO ϕ y . The first and second terms are very small, because the wave functions of cluster orbital, u x and u y , are so smooth that the derivative of the ionic potential scarcely contributes to the SOI in the form of Equation (8). The main contribution comes from the last term [112].…”

Section: Mott Insulator and Canted Antiferromagnetism In K-loaded Zeomentioning

confidence: 99%

“…A new paradigm of electronic system can be provided by the alkali-metal loading into zeolites. Up to now, comprehensive researches have been carried out , especially on magnetic properties [1,2,9,11,[13][14][15][16][17][18][23][24][25][26][27][28][29][30][31][34][35][36][37]39,41,[43][44][45][46]48,50,51], optical properties [1,3,7,24,38,49,53], electrical properties [42,43,49,50,52,53], structural analyses [8,12,22,47] and theoretical calculations …”

Section: Introductionmentioning

confidence: 99%

“…In channel type zeolites, the one-dimensional wave functions can be expected for s-electrons, such as potassium metals in the bundle of cylindrical channels of zeolite L (the framework structure type of LTL) [4,8,53]. Other guest materials are also loaded into porous materials.…”

Section: Introductionmentioning

confidence: 99%

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Electrons of alkali metals in regular nanospaces of zeolites

Nakano

Nozue

2017

Advances in Physics: X

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The s-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 freeelectrons. Alkali-metal clusters are stabilized in cages of zeolites, and new quantum states of s-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 of s-electrons play critical roles in taking on the novel electronic properties. Electronic properties can be overviewed systematically by a coarse-grained model of localized s-electron states in cages based on the tightbinding approximation, followed by the t-U-S-n diagram of the correlated polaron system given by the so-called HolsteinHubbard Hamiltonian: an electron transfer energy through windows of cages (t), a Coulomb repulsion energy between two s-electrons in the same cage (U), a short-range electron-phonon interaction energy due to the cation displacements (S), and an average number of s-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. ARTICLE HISTORY

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Section: Mott Insulator and Canted Antiferromagnetism In K-loaded Zeomentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electrons of alkali metals in regular nanospaces of zeolites

Nakano

Nozue

2017

Advances in Physics: X

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“…And the scarce attempts of the classical contact dc resistivity measurements have failed for these compounds 6. Prompted by similar problems, we have applied here the nonintrusive microwave cavity perturbation (MWCP) technique to measure the ac electrical conductivity of powder samples without the need for sample contacts 7. At high frequencies (here 3.2 GHz), the effects of powder intergrain contacts are negligible, and the microwave method thus probes directly the intragrain conductivity.…”

mentioning

confidence: 99%

“…At high frequencies (here 3.2 GHz), the effects of powder intergrain contacts are negligible, and the microwave method thus probes directly the intragrain conductivity. The details of the equipment used and of the quantitative analysis of the electric conductivity are described elsewhere 7.…”

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confidence: 99%

“Unconventional covalent” KAgF₃ is metallic above 50 K

Grochala

Edwards

2003

Physica Status Solidi (b)

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. 30.+h, 72.80.Ga, 74.10.+v Using microwave cavity perturbation and magnetic susceptibility measurements we demonstrate for the first time that for KAgF 3 the antiferromagnet-paramagnet transition leads to metallic state above 50 K.Are fluorides always prototypical ionic insulators? Is it possible that electrons hop between metal centers via deep-lying F(2p) orbitals [1], thus leading to metallic conductivity, in analogy to many conducting oxides? Could the strongly-bound d electrons of Ag(II), spatially localized around nuclei, be set free to move at a moderate temperature? Or, in yet another words, how deep in the absolute energy scale could the Fermi level of a metallic substance could lye? In order to answer these fundamental questions we are currently exploring the challenging chemistry of high oxidation states in multinary silver fluorides, at the very limits of the positive redox potentials.Over sixty fluorides of Ag(II) (fluoroargentates) are known, among which only seven, representing the MAgF 3 and M 2 AgF 4 families (M = Cs, Rb, K) and the binary AgF 2 , have extended pseudo-2D structures (see Fig. 1) [2].The electrical properties of these substances are of particular interest because fluoroargentates are isoelectronic and sometimes also isostructural (K 2 AgF 4 ≈ La 2 CuO 4 ) with the oxides of Cu(II); the latter become high temperature superconductors under proper doping. DFT computations [3] and ultra-high resolution XPS spectroscopical results [4] indicate strong mixing of the Ag(4d) and F(2p) levels, which may lead to metallic [5], and possibly even superconducting behaviour. However, measuring the electrical conductivity of strongly oxidizing and highly air-and moisture-sensitive microcrystalline powders, such as fluoroargentates, presents a formidable experimental challenge. And the scarce attempts of the classical contact dc resistivity measurements have failed for these compounds [6]. Prompted by similar problems, we have applied here the nonintrusive microwave cavity perturbation (MWCP) technique to measure the ac electrical conductivity of powder samples without the need for sample contacts [7]. At high frequencies (here 3.2 GHz), the effects of powder intergrain contacts are negligible, and the microwave method thus probes directly the intragrain conductivity. The details of the equipment used and of the quantitative analysis of the electric conductivity are described elsewhere [7].The variation of the resonance microwave frequency, ν, and of the resonance band width, ∆ν ½ , [8] for powder samples of KAgF 3 and AgF 2 (referenced to an empty glass tube), are shown in Fig. 2.

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