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'Zeolite' in keywords Facet   section ZfN Section A  [X]
Facet   Publication Year 1996  [X]
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1Author    F. Ucun, F. KöksalRequires cookie*
 Title    An EPR Study on V0 2+ and Mn 2+ Ions in Some Zeolites  
 Abstract    The electron paramagnetic resonance (EPR) of hydrated V0S0 4 -3H 2 0 and MnCl 2 -2H 2 0, adsorbed on the synthetic zeolites 3A, 4A, 5A and 13X of pore diameters 0.3, 0.4, 0.5, and 1.0 nm, respectively, and the natural zeolites heulandite and clinoptilolite was investigated. The spectra indicated that the coordination structures are V0(H 2 0)5 + and Mn(H 2 0)g + , and that their EPR line widths vary with the pore diameters and the surface areas of the zeolites. The spectra of V0(H 2 0)5 + in natural zeolites at room temperature display an isotropic behavior and therefore indicate that the water ligands are mobile. The EPR spin Hamiltonian parameters, the molecule orbital constant ß* 2 , and the Fermi contact term K e[[ were determined and are discussed. The spectra of Mn(H 2 0)^ for narrow-pore zeolites indicate the existence of mobile and immobile water, whereas for wide-pore and natural zeolites they indicated the existence of only mobile water. The obtained Mn(H 2 Ö)g + spectra are discussed. 
  Reference    Z. Naturforsch. 51a, 23—26 (1996); received October 17 1995 
  Published    1996 
  Keywords    EPR, V0 2 +, Mn 2 +, Zeolites, Coordination 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0023.pdf 
 Identifier    ZNA-1996-51a-0023 
 Volume    51 
2Author    Fevzi Köksal, Fatih Ucun, İbrahim KartalRequires cookie*
 Title    EPR Study of Cr 5 + and Cu 2 + in Some Zeolites Introduced by Solid-and Liquid-State Reactions  
 Abstract    This study reports on the EPR of Cr 5+ and Cu 2+ ions, introduced by solid-and liquid-state reactions with the synthetic zeolites 3A, 4A and 5A, and the natural zeolite clinoptilolite. Cr 3+ was oxidized to Cr 5 + in the samples, the coordination around Cr 5 + being square pyramidal. Super-hyperfine (shf) interaction of Cr with 27 A1 nucleus was observed in both solid-and liquid-state-introduced 5A zeolite, whereas this shf could not be observed for the solid-state introduced 4A zeolite. The liquid-state Cr-introduced 4A zeolite needed a heat treatment at 473 K for Vi h for the appearance of shfs. Furthermore, it has been found that the coordination structure around the Cu 2 + is square pyramidal in solid-state introduced samples, whereas it is octahedral in the liquid-state introduced ones. 
  Reference    Z. Naturforsch. 51a, 242—244 (1996); received January 8 1996 
  Published    1996 
  Keywords    EPR, Cu 2 +, Cr 5 +, Zeolites, Ion introduction 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0242.pdf 
 Identifier    ZNA-1996-51a-0242 
 Volume    51