Möller, Karin; Bein, Thomas; Brinker, C. J.
Oxometalate-glass composites and thin films.
In: Materials Research Society Symposium Proceedings, Vol. 180: pp. 595-604
New glass-composites with ion exchange properties have been developed.
Ammonium 12-molybdophosphate (AMP) (ΝΗ4)3ΡΜοΐ2θ4ο, and ammonium 12-tungstophosphate (AWP) (Nh4)3PW12O40, known for their ion exchange
capabilities, are included either in preformed aerogels with defined pore size, or are
added to sol-gel mixtures during the process of gel formation. Characterization is
carried out by FTIR, Raman and EXAFS spectroscopy. Ion exchange capacities for the
oxometalate precursors are determined for silver and rubidium and are compared to
those of the glass composites. Glass composites show high ion exchange capacity, but
some portion of the metalate complexes leaches from the glass during the procedure.
This is in contrast to thin composite films, which have almost no porosity and do not
show loss of metalate. EXAFS spectroscopy demostrates that the oxometalate
microstructure is maintained in glass composites and that rubidium ions after ion
exchange in glasses occupy similar cation positions as in the precursor compounds.