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The Pechini and microwave-assisted hydrothermal syntheses of nanocrystalline Er
and Tm
co-doped MY(WO
)
, where M = Li, Na, K, double tungstates are reported. The obtained samples were characterized using standard X-ray powder diffraction (XRD) technique, Rietveld method, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and IR spectroscopy. The smallest crystallites (about 13 nm) could be obtained for the sodium samples synthesized by both the Pechini (for the resin calcined at 550 °C) and hydrothermal methods (synthesis at 230 °C). The average particle size of nanocrystalline powders increases with increasing temperature. It was found that nanocrystals retain the bulk structure with tetragonal and monoclinic symmetry for the sodium and potassium analogues, respectively. In contrast to this behaviour, LiY(WO
)
undergoes a size-induced structural transformation from monoclinic (space group
2/
) to tetragonal (space group
4
/
) symmetry. IR spectra of the synthesized sodium and potassium compounds are very similar to their bulk counterparts. IR spectra of the lithium analogues show, however, abrupt changes when the calcination temperature increases to 850 °C or higher. This behaviour is consistent with the size-induced phase transition in this compound.
Sprache
Englisch
Identifikatoren
ISSN: 2046-2069
eISSN: 2046-2069
DOI: 10.1039/C7RA10706D
Titel-ID: cdi_crossref_primary_10_1039_C7RA10706D
Format
–
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