An X-ray Diffraction Study of Na, Ag-A Reduced by Hydrogen. Ag $_3\;^+$ and Ag $_3\;^{2+}$ Clusters

The reduction of vacuum-dehydrated , and its reoxidation by O, have been studied by X-ray powder diffraction. Also, the structure of treated with hydrogen at room temperature has been studied by single crystal methods in the cubic space group Pm3m at . The diffraction pattern of dehydrated Ag-A reduced by H contains only the (111) and (200) reflections of silver metal, indicationg that the zeolite structure has been lost, but the zeolite's diffraction pattern and structural integrity can be fully restored by oxidation with O at 100 or 200. In contrast, the structures of , x = 4.5 and 9.2, were not destroyed by treatment with hydrogen. Dehydrated Na-A treated with 50 Torr of hydrogen gas at 24 for 30 minutes has ions at 6-ring sites. These $Ag^+ ions are associated with 2.54 Ag atoms to form 1.27 clusters per unit cell. Also found were 0.7 clusters per unit cell near the 8-rings. The structure was refined to the final error indices R = 0.134 and R (weighted) = 0.147, using 168 independent reflections for which $I_0 >3{\sigma}(I_0)$.