2004 Lanthanoids

LanthanoidsI 2800 Novel Microporous Lanthanoid Silicates with Tobermorite-Like Structure. —

The compounds Na1.08K0.5Ln1.14Si3O8.5·1.78H2O (Ln: Eu, Tb, Sm, Ce) are synthesized from aqueous alkaline solutions of SiO2, Na2O, KOH, NaOH, and LnCl3 (autoclave, 230 °C, 3 d). The samples are characterized by powder XRD, SEM, 23Na and 29Si MAS NMR, and luminescence spectroscopy. The structure of the solids is closely related to that of mineral tobermorite. The Eu-containing compound crystallizes in the monoclin-ic space group B11m with Z = 4. The materials combine microporosity with interesting photoluminescene properties, and their structural flexibility allows fine-tuning of lumi-nescence properties by introducing a second type of lanthanide ion into the framework. Thus, these materials may find applications in new type of sensors. — (FERREIRA, A.; ANANIAS, D.; CARLOS, L. D.; MORAIS, C. M.; ROCHA*, J.; J. Am. Chem. Soc. 125 (2003) 47, 14573-14579; Dep. Chem., Univ. Aveiro, P-3810 Aveiro, Port.; Eng.) — W. Pewestorf

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