Nuclear Quadrupole Coupling Tensors for Na23 and Al27 in Natrolite, a Fibrous Zeolite

Abstract

The nuclear magnetic resonance spectra of Na²³ and Al²⁷ in a single crystal of natrolite (Na₂Al₂Si₃O₁₀·2H₂O), a fibrous zeolite, have been investigated at room temperature in an external magnetic field of 7380 gauss. It was found that the sodium and aluminum atoms each occupy a single chemically unique site in the unit cell. The quadrupole coupling constants and asymmetry parameters of the electric field gradient tensors at these sites were determined to be $$\begin{array}{ccc}& \mathrm{\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}}{\mathrm{Na}}^{23}& \mathrm{\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}}{\mathrm{Al}}^{27}\\ \mathrm{eqQ/h}& \text{1759.3±0.3\hspace{0.17em}}\mathrm{kc}/\sec & \text{1663.3±0.2\hspace{0.17em}}\mathrm{kc}/\sec \\ \eta & \text{0.6427±0.0004}& \text{0.5029±0.0005.}\end{array}$$ The orientations of the principal axes of the electric field gradient tensors for the above sites and their symmetry‐related sites have also been determined.