Fluoridhaltige Gäste in Alumosilicaten: Tetrafluoroborate in dem Sodalithen Na8Al6Si6O24(BF4)2 |
| |
Authors: | Marina M Lezhnina Edgar Jordan Sergej A Klimin Jürgen Löns Hubert Koller Boris N Mavrin Ulrich Kynast Prof Dr |
| |
Institution: | 1. University of Applied Sciences, Fachhochschule Münster, FB Chemieingenieurwesen, Stegerwaldstra?e 39, 48565 Steinfurt, Germany, Fax: +49‐2551‐962119;2. Mari State Technical University, Institute of Physics, Yoshkar‐Ola, Russia;3. University of Münster, Institutes of Physical Chemistry and Mineralogy, Münster, Germany;4. Russian Academy of Sciences, Institute of Spectroscopy, Troitsk, Russia |
| |
Abstract: | In the course of investigations on optical properties resulting from the interaction of fluorides with alumosilicate host materials and rare earth guests, a well defined BF4– ion wasfound to be incorporated within the sodalite of composition Na8Al6Si6O24(BF4)2. The resulting cubic molecular structure, which was determined by Rietveld methods (space group P4 n, a = 906.91 pm, wRp = 0.045, Rp = 0.027), contains one anion in each sodalite cage and is, contrarily to expectations, thermally stable. NMR spectroscopic investigations indicated a fast rotatory motion of the BF4– tetrahedra at room temperature and agreed with the tetrahedral BF4– ions found in IR and Raman spectra. Preliminary attempts to obtain a luminescent material by incorporation of Eu3+ through aqueous ion exchange only yielded low rare earth concentrations, giving rise to characteristic red emission lines at 581 nm (5D0 → 7F1) and 615 nm (5D0 → 7F2) in a 1:2 intensity ratio. The material unexpectedly exhibited a strong broad band emission at 520 nm after calcination under Ar, which is attributed to the formation of an Eu2+ species. Further calcination under air partially reestablished the Eu3+ emission. |
| |
Keywords: | Sodalites Fluorides Europium Luminescence Lanthanides |
|
|