Rietveld refinement and solid state NMR study of Nd-, Sm-, Gd-, and Dy-containing Y zeolites

Nery, José Geraldo; Giotto, Marcus; Mascarenhas, Yvonne P.; Cardoso, Dilson; Zotin, Fátima Marı́a Zanon; Sousa-Aguiar, Eduardo Falabella

doi:10.1016/s1387-1811(00)00304-8

Cited by 70 publications

(23 citation statements)

References 35 publications

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“…[27] According to the reaction stoichiometry, which agrees well with the refined occupancies, [18] only one-third of these sites can be filled. If we assume full occupancy in a single cage, only 2.5 cages can be filled out of eight total in the unit cell.…”

Section: Atomic Pdf Resultssupporting

confidence: 72%

X-Ray Scattering Studies of HgSe Nanoclusters in Zeolite

Abeykoon

Castro-Colín

Anokhina

et al. 2008

Metall Mater Trans A

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Structural studies done on HgSe nanoclusters fabricated in the pores of two types of zeolite frameworks, LTL (tubular pore) and Nd-Y (nearly spherical pore), are presented. Nanoclusters were synthesized in these zeolite frameworks via chemical vapor deposition. Anomalous X-ray scattering (AXS) studies were performed on both HgSe/zeolite-Y and HgSe/zeolite-L systems. As a result, we present two distinct structural models for NdY/HgSe and LTL/HgSe systems. A remarkable feature present in our X-ray diffraction (XRD) patterns, diffuse scattering, will also be discussed using our initial results of the atomic pair distribution function (PDF) studies. X-ray structural work is complemented using the results of optical and Raman studies.

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Section: Atomic Pdf Resultssupporting

confidence: 72%

X-Ray Scattering Studies of HgSe Nanoclusters in Zeolite

Abeykoon

Castro-Colín

Anokhina

et al. 2008

Metall Mater Trans A

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“…The refined lattice parameter, 24.681 22͑2͒ Å, shows an ϳ0.03 Å expansion with respect to the lattice parameters of the empty NdY. The atomic arrangement still obeys Fd-3m symmetry preserving the basic shape of the NdY framework.…”

Section: Anomalous X-ray Scattering Data Refinementmentioning

confidence: 87%

“…The effective volume of the channels of LTL is free of cations and can be used for the nanocluster fabrication followed by dehydration. However, in Na-Y, extra-framework cations ͑Na + ͒ occupy sites SI, SIV, and SV, 24 blocking the main cage. An ionic exchange was performed on Na-Y to remove Na + from the main cavities and to limit the resulting Nd 3+ to SI and SIЈ sites 24 according to the method described below.…”

Section: A Nanocluster Synthesismentioning

confidence: 99%

Synchrotron x-ray and optical studies of the structure of HgSe semiconductor nanoclusters confined in zeolite L and zeolite Y

et al. 2008

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HgSe semiconductor nanoclusters were fabricated in nearly spherical pores of zeolite Y and one-dimensional ͑1D͒ tubular pores of zeolite L. Anomalous x-ray scattering ͑AXS͒ data sets were collected on both HgSe/ zeolite Y and HgSe/zeolite L systems, together with optical studies ͑Raman and UV-visible absorption͒. Two distinct structural models were determined by performing the Rietveld refinement on AXS data sets. Given the existence of a pronounced diffuse scattering in both filled zeolites and our refined models without the observed diffuse background, for each system, we propose the existence of an average HgSe nanocluster or a 1D nanostructure and the related disorder within the nanocluster which gives off the diffuse scattering. Optical studies were used to complement our x-ray structural work.

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“…Rare earth cations in the sodalite cages, which were associated with the coordination between the cations and the framework oxygen atoms, stabilized the zeolite structure [27,28]. Notably, when Ce(OH) 3 was calcined, cerium ions were gradually oxidized to higher valence owing to the lower standard molar Gibbs energy of CeO 2 and the inhibited migration of tetravalent cerium [24,29].…”

Section: Resultsmentioning

confidence: 99%