Janssen, R.; Tijink, G.a.h.; Veeman, W.s.; Maesen, T.l.m.; Van Lent, J.f.:
High-temperature NMR study of zeolite Na-A: detection of a phase transition.
1989
In: Journal of Physical Chemistry (J.Phys.Chem.), Jg. 93 (1989), Heft 2, S. 899 - 904
Artikel/Aufsatz in Zeitschrift1989Chemie
Titel:
High-temperature NMR study of zeolite Na-A: detection of a phase transition.
Autor(in):
Janssen, R.; Tijink, G.a.h.; Veeman, W.s.LSF; Maesen, T.l.m.; Van Lent, J.f.
Erscheinungsjahr
1989
Erschienen in:
Titel:
Journal of Physical Chemistry (J.Phys.Chem.)
in:
Jg. 93 (1989), Heft 2, S. 899 - 904
ISSN:

Abstract:

The zeolite Linde 4A was studied by 23Na, 27Al, and 2.Si NMR at ?953 K. 23Na NMR shows that the quadrupole interaction of Na ions sited at 6-rings decreases when the temp. increases. With the aid of 2-dimensional nutation and exchange expts. it can be shown that large-amplitude motions of the Na ions, which in principle could explain a decrease of quadrupole interactions, do not occur. The decrease of the quadrupole interaction can be interpreted in terms of a phase transition. A comparison of the NMR spectra of 23Na and 27Al shows that the zeolite framework undergoes a major structural change upon increasing the temp., before the Na ions are displaced at higher temps. The exchange of Na ions for K ions shifts this transition to higher temps.