Nuclear gamma resonance NGR data

The iron silicates with the mordenite type stractrrre were studied by Fe NGR method [71G1, 92C1]. Some spectra are shown in Fig. 27 [92C1]. The data indicated the presence of most of the iron ions as high-spin Fe in nearly symmetric tetrahedral sites - Table 9. At low temperature (4.2 K), in a field of 4.13 T, an average internal field of 46(1) T was shown [92C1]. 

The tin zeolites M-Sn-MOR and T-Sn-MOR were studied by Sn NGR method [94H1] - Table 9. For samples, e.g., M-Sn-MOR, prepared by microwave-assisted hydrolysis of oi notin chloride (Chap. 8.1.6.8.1 in this volume), the Sn NGR spectra depicted a single peak close to zero velocity. These spectra were attributed to the presence of tin exclusively in finely dispersed Sn02- For T-Sn-MOR samples, prepared from Na-MOR and either Sn -chloride or Sn -sulfate, the spectra arise exclusively from Sn in dispersed oxide. In case of T-Sn-MOR prepared from H-mordenite and Sn -cloride, an additional doublet appeared. This has been attributed to residual Sn species present as impurity. 

The composites prepared by hydrolysis of antimony pentachloride in the presence of the zeohte mordenite have been studied by Sb NGR - Fig. 29 [94H2]. The spectra show a single line located close to zero velocity, consistent with Sb present in Sb Oe octahedra. There were reported to be differences in the distributions of local geometries for Sb Oe octahedra. Consequently, the spectra were reported to be consistent with an antimony-containing phase of the composites (amorphous antimonic acid), as would be anticipated from the preparative conditions. 

---