Si-29 MAS NMR and Raman spectroscopy studies of synthetic microporous (Zr,Hf)-umbite


Solid Solutions of synthetic analogues of the microporous mixed tetrahedra-octahedra mineral umbite K-2[(Zr1-xHfx)Si3O9](H2O)-H-. (x = 0, 0.17, 0.33, 0.5, 0.67, 0.83 and 1) have been Successfully prepared via hydrothermal synthesis. The materials have been characterised by Si-29 magic-angle spinning (MAS) NMR and Raman spectroscopy, powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS). Si-29 MAS NMR provides clear evidence for the framework substitution of Hf or Zr, which is not forthcoming from other techniques. The hafnium content, x, may be estimated from the intensity of the Si-29 MAS NMR resonances and Raman shifts of bands in the range 880-1000 cm(-1).






Lin, Z; Rocha, J

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