摘要:

X ray absorption edges and preedges together with Fourier transforms of the EXAFS signal of the LaCo(fsa)2en,NO3complex ((fsa)2en ˭N,N′-bis(3-carboxysalicydene)ethylenediamine) alone or intercalated in montmorillonite and taeniolite have been studied as a function of temperature. A preferential orientation of the complex has been found when it is intercalated in the silicates. Upon applying thermal treatment, it undergoes similar decomposition whatever it is free or in taeniolite. Due to the thermal stability of taeniolite layers, a taeniolite-LaCoO3layered nanocomposite could be formed. On the other hand, we have shown that being in montmorillonite, the cobalt oxide phase is reduced progressively above 270°C.

ISSN:1058-725X    

DOI:10.1080/10587259808042399

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Chiral modification of K-10 montmorillonite was carried out with chiral amine salts. The ion-exchanged K-10 samples were characterized by CHN analysis, XRD, FT-IR and29Si NMR spectroscopies and tested in catalytic reactions.

ISSN:1058-725X    

DOI:10.1080/10587259808042400

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

LaCo(fsa)2en-Montmorillonite and LaCo(fsa)2en-Taeniolite ((fsa)2en ˭N,N′-bis(3-carboxysalicydene)ethylenediamine) derivatives have been synthesized by cationic exchange and characterized. The thermal treatment of the exchanged clays under oxidizing atmosphere led to the formation of nanocomposites above about 300°C. It has been shown that the LaCoOy-Montmorillonite nanocomposite is stable up to about 550°C versus 700°C for the LaCoOy-Taeniolite nanocomposite. Both are constituted of oxide pillars (diameter 20–40Å) intercalated within the silicate matrix.

ISSN:1058-725X    

DOI:10.1080/10587259808042401

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Three copper complex ions, [Cu(en)2]2+, [Cu(cyclam)]2+, and [Cu(H2O)4]2+are intercalated into a layered silicate, Hectorite (Hec), by ion exchange reaction. According to the powder XRD analysis, the basal increments of 3.21 Å for [Cu(en)2]2+-Hec, 3.81Å for [Cu(cyclam)]2+-Hec, and 2.43Å for [Cu(H2O)4]2+- Hec indicate that the local geometry around copper (II) is square planar for all the intercalates. XANES results show the characteristic peak of square planar structure due to the ligand to metal charge transfer (LMCT) effect, which is shifted to lower energy side with an order of 0.5∼1.6eV but the main edges due to 1s → 4pxand 1s → 4p[sgrave]transitions are shifted to higher energy side for about 0.5∼1.5eV compared to precursor depending on the ligands From Cu K-edge EXAFS analysis, it is found that four nitrogen atoms at ∼2.0Å and two oxygen atoms at ∼2.4Å are coordinated with copper(II) in precursor salts, but only four nearest neighbors are coordinated to copper (II) at ∼2.0Å in the intercalated complexes

ISSN:1058-725X    

DOI:10.1080/10587259808042402

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Various metal-cluster ion intercalated clays with first stage-and second stage-like structures were successfully synthesized and their physicochemical properties were examined briefly.

ISSN:1058-725X    

DOI:10.1080/10587259808042403

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Chromia pillared clay was prepared by ion exchange type intercalation reaction between Na-montmorillonite and the trimeric chromium oxyformate (TCF) salt in an aqueous solution. According to powder XRD, the basal spacing of 16.4 Å upon intercalation of TCF ion suggests that the Cr3O plane is parallel to the aluminosilicate layers with a gallery height of ∼6.8 Å Even though the basal spacing decreases slightly upon heating, the layer structure is retained and beyond 400 °C it transforms into microporous Cr2O3pillared montmorillonite with BET specific surface area of 152 m2/g XANES spectroscopy confirms that the trivalent chromium ion is stabilized in the interlayer space without any further oxidation to higher valence upon heat treatment According to the EXAFS spectroscopic analysis, the Cr-Cr bond length (3 29 Å) of vertex-linkaged CrO6octahedron in the precursor TCF splits into 2.64 Å, 2 98 Å, and 3.77 Å during the calcination, due to the face-, edge-, and corner-linkaged CrO6octahedra, respectively, similar to the chromium oxide, Cr2O3.

ISSN:1058-725X    

DOI:10.1080/10587259808042404

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Succesful attempt was made to intercalate silicate between the layers of sheet silicate magadiite. Both the interlayer distance and the BET value increased as the result of layers propped apart. SEM images evidence structure changes occured.

ISSN:1058-725X    

DOI:10.1080/10587259808042405

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Layered hydrated birnessite-type manganese oxides have been intercalated withn-alkylammonium ions by ion-exchange for interlayer sodium or potassium, and by acid-base reactions. The expanded phases have modified interlayer environments and can be used as precursors for intercalation of aniline, which is oxidised and polymerised between the layers.

ISSN:1058-725X    

DOI:10.1080/10587259808042406

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Pd and CdS nanoparticles have beenin situgenerated in the adsorption layers of hexadecylammonium montmorillonite (HDAM) and hexadecylpyridinium montmorillonite (HDPM) clay organo-complexes. The clay intercalated Pd and CdS materials may find applications as catalysts and semiconductors, respectively. Information on the structure of clay intercalated nanoparticles have been obtained from X-ray diffraction and small angle X-ray scattering measurements.

ISSN:1058-725X    

DOI:10.1080/10587259808042407

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Vermiculite was intercalated with alkali metals by vapor transport. Synchrotron x-ray, Raman and neutron scattering experiments were conducted to study the structure and lattice dynamics of the new intercalation compounds. Also, magnetization measurements were carried out with use of a SQUID. A drastic increase in conductivity upon intercalation and its relationship to the structure and charge transfer are discussed.

ISSN:1058-725X    

DOI:10.1080/10587259808042408

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor