A combined experimental and theoretical study of the simultaneous occupation of SIa and SI′ sites in fully dehydrated K–LSX

Guesmi, Hazar; Massiani, Pascale; Nouali, Habiba; Paillaud, Jean-Louis

doi:10.1016/j.micromeso.2012.04.011

Cited by 28 publications

(16 citation statements)

References 24 publications

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“…We already reported similar delocalization of site I for K + or Ni 2+ on comparable systems as deduced from EXAFS, X-ray or DFT data. 35,38,41 Moreover, this affinity governs not only the location of nickel and its migration upon (de)hydration, but also that of sodium (as further discussed in Section 3.4).…”

Section: 2) Ni 2+ and Na + Cations Locationsmentioning

confidence: 99%

Cation Migration and Structural Deformations upon Dehydration of Nickel-Exchanged NaY Zeolite: A Combined Neutron Diffraction and Monte Carlo Study

et al. 2016

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Section: 2) Ni 2+ and Na + Cations Locationsmentioning

confidence: 99%

Cation Migration and Structural Deformations upon Dehydration of Nickel-Exchanged NaY Zeolite: A Combined Neutron Diffraction and Monte Carlo Study

et al. 2016

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“…Cations are located at the center of the hexagonal prism of D6R (site I), both sides of D6R in β-cages (site IA), near the center of S6R in supercage (site II), and at the side of 4R in supercage (site IIIA). 16) K cations occupy sites I and IA in dehydrated K 12 -LSX, 17) where sites I and IA are indicated by SI (SIa) and SIA, respectively, in Ref. 17.…”

Section: Zeolite Lsx and The Loading Of Alkali Metalsmentioning

confidence: 99%

“…16) K cations occupy sites I and IA in dehydrated K 12 -LSX, 17) where sites I and IA are indicated by SI (SIa) and SIA, respectively, in Ref. 17. Na cations preferably occupy sites IA and II without site I in Na-form X.…”

Section: Zeolite Lsx and The Loading Of Alkali Metalsmentioning

confidence: 99%

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Ferromagnetism of Na–K Alloy Clusters Incorporated in Zeolite Low-Silica X

et al. 2015

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In a porous crystal of zeolite low-silica X (LSX), β-cages and supercages (cavities) are arrayed in a diamond structure, respectively. We loaded potassium metal into zeolite LSX which has a chemical formula of Na 7.3 K 4.7 Al 12 Si 12 O 48 per β-cage (or supercage), and generated Na-K alloy clusters in β-cages and=or supercages. We have investigated the magnetic properties, the optical ones and the electrical resistivity at various values of K-loading density n per β-cage (or supercage) up to n = 9.7. Localized magnetic moments are observed at 8.2 < n < 9.7. Almost simultaneously, nearly pure ferromagnetism is observed at 8.4 < n < 9.7. The highest Curie temperature is ≈12 K at n ≈ 9. Optical reflection spectra for 8 < n have a new band at 2.8 eV which is assigned to the optical excitation of s-electrons of clusters generated at β-cages. The origin of the magnetic moments is assigned to these β-cage clusters because of the coincidence between the growths of the 2.8 eV band and localized magnetic moments. The origin of magnetic ordering is explained by a ferromagnetic interaction between β-cage clusters. All samples are found to be insulating from the temperature dependence of electrical resistivity. A direct magnetic interaction between β-cage clusters is not expected because of the high electronic barrier between them. A ferromagnetic superexchange coupling between β-cage clusters is newly proposed via the sp 3 -like closed-shell clusters at supercages. A thermal hysteresis is observed in the electrical resistivity at intermediate temperatures, and the origin is assigned to low-density carriers generated in the Na-K eutectic alloy structures in nanospace.

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“…The bottles were taken out of the oven and quenched in cold water after specified lengths of time. The product in each autoclave was filtered and the solid phase was washed by using 0.01 M sodium hydroxide instead of water to avoid over washing and hydrolysis [32]. The solid materials which are intermediates were then dried in air at room temperature and kept in tightly sealed glass vials for analysis.…”

Section: Introductionmentioning

confidence: 99%

An investigation into the crystallization of low-silica X zeolite

Zhang

Huang

2015

J Porous Mater

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The crystallization of low-silica X (LSX) zeolite with FAU topology was examined under hydrothermal synthesis conditions. PXRD was employed to follow the evolution of the long-range ordering of the gel. Raman spectra provided information on various ring and cage species existing in the gel. 27 Al and 29 Si solid-state NMR spectroscopy was utilized to monitor the change in local environment of tetrahedral sites. The results indicate that an amorphous aluminosilicate phase was formed immediately upon mixing different reactive species. Hydrothermal treatment led to the formation of sodalite-cage like species and the species with larger cavities, joint four-member rings (4Rs) and branched 4Rs, which are the structural building units of the FAU framework. These units were assembled into the crystalline structure of LSX zeolite. 23 Na and 39 K solid-state NMR results show that the transformation process was accompanied by the changes of the local structure of hydrated Na ? and K ? ions. The two types of cations may work synergistically to template the crystallization of LSX zeolite.

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A combined experimental and theoretical study of the simultaneous occupation of SIa and SI′ sites in fully dehydrated K–LSX

Cited by 28 publications

References 24 publications

Cation Migration and Structural Deformations upon Dehydration of Nickel-Exchanged NaY Zeolite: A Combined Neutron Diffraction and Monte Carlo Study

Cation Migration and Structural Deformations upon Dehydration of Nickel-Exchanged NaY Zeolite: A Combined Neutron Diffraction and Monte Carlo Study

Ferromagnetism of Na–K Alloy Clusters Incorporated in Zeolite Low-Silica X

An investigation into the crystallization of low-silica X zeolite

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