Mössbauer Spectroscopy Applied to Inorganic Materials

Tandem Reduction–Reoxidation Augments the Catalytic Activity of Sn-Beta Zeolites by Redispersion and Respeciation of SnO2 Clusters

“…% sample, reflecting the higher incorporation of tetrahedral framework Sn sites in samples with low Sn loading. 49,58 Moreover, tetrahedral framework Sn sites also increase the QS values compared to the octahedral SnO2 species. Hence, relatively higher QS values for the two-step calcination process sample indicate an increase in the distortion of the Sn(IV) environment for these sites.…”

“…This is indeed observed for the IS values of the two-step calcination process (N 2 /air) samples compared to the single-air step counterparts (Table 1, entries 4−6), and a higher negative IS shift is observed for the 2 wt % sample, reflecting the higher incorporation of tetrahedral framework Sn sites in samples with low Sn loading. 49,58 Moreover, tetrahedral framework Sn sites also increase the QS values compared to the octahedral SnO 2 species. Hence, relatively higher QS values for the twostep calcination process sample indicate an increase in the distortion of the Sn(IV) environment for these sites.…”

“…49 As tetrahedral bonding requires a larger contribution from p electrons compared to octahedral Sn in SnO 2 , the tetrahedral framework Sn sites will possess lower IS values relative to the octahedral SnO 2 sites. 49,58,59 For the samples studied here, the Sn(IV) envelope of their Mossbauer spectra contains both contributions, but due to the relatively low QS values, the Sn(IV) species are difficult to be distinguished (deconvoluted in the fittings), and so they are modeled by a single component acquiring the average IS value of these contributions. However, an increase in the amount of tetrahedral framework Sn sites will shift the IS of the Sn(IV) component toward lower average values.…”