Silicon-29 magic-angle-spinning nuclear magnetic resonance study of the crystalline–amorphous transition of zeolite A containing trapped krypton
High-resolution solid-state 29Si n.m.r. and i.r. spectroscopies have been used to monitor the crystalline–amorphous transition of (Ca, Na)-and (Sr, Na)-exchanged zeolites A hydrothermally treated in the presence of densified krypton gas. Both techniques are capable of monitoring the transition on a smaller scale than X-ray diffraction and demonstrate that thermally stable gas fixation takes place in a truly amorphous glassy matrix.