Ordered distribution of aluminium or gallium atoms in zeolite L

The ordered distribution of aluminium or gallium atoms in the framework of zeolite L has been determined by analysing 29Si magic-angle-spinning (m.a.s.) n.m.r. spectra. As a first step, an ideal crystal with no defects was investigated; subsequently a small number of defect atoms were introduced and a best fit was obtained between calculated and observed 29Si n.m.r. spectra. Zeolite L has a doubled c constant and belongs to the space group symmetry P63. The proposed model explains the geometries and properties of extra-framework cation sites.