Local environment and vibrational characteristics of 119Sn(II) Mössbauer probe atoms located on the surface of Cr2O3 microcrystals

Mössbauer-spectroscopic Characterization of the Local Surrounding of Tin Dopant Cations in the Bulk and on the Surface of YCrO3 Crystallites

“…This reaction probably involves only the attachment of an oxygen atom to the lone pair of electrons of a surface-located Sn 2+ , without any significant change in the cationic surrounding of the oxidized Sn 4+ . The validity of such an assumption has been experimentally proven for tin ions on the surface of Cr 2 O 3 [15].…”

“…This leads to a drastic decrease of the spin polarization of Sn 2+ as compared to Sn 4+ . For instance, the H value was found to be 2.5 times lower for Sn 2+ on the surface of Cr 2 O 3 [15] and about 13 times lower for Sn 2+ in the bulk of α-MnS (containing both Sn 2+ and Sn 4+ ions on the sites with a similar cationic surrounding) [16]. Accordingly, for the value of 35 kOe, relative to the "daughter" Sn 4+ (sample 2 ox ), a value of H ranging from 14 to 3 kOe is to be anticipated at 100 K for the parent 119 Sn 2+ (sample 2).…”

Mössbauer study of the Impact of Hydrogen Fluoride on Tin Probe Ions Located on the Surface of Cr2O3 microcrystals

“…The "nal treatment is performed under H #ow at 1200 K for 10 h in a quartz reactor equipped with a lateral thin-window sample cell for in situ MoK ssbauer measurements. At the end of this annealing the tin ions are reduced to the #II state and located at the interface +Cr O crystallites/H , (1,7). This surface location is in particular re#ected by the high sensitivity of the Sn(II) ions to air exposure which results in their instantaneous reoxidation to the #IV state.…”

“…Predominant part of the Sn(II) ions are surrounded by three Cr(III) inducing H"47.2 kOe while the others have only one Cr(III) neighbor (H"11.2 kOe). The "rst are located in the topmost cationic layer, the last just above this layer (&&over-surface'' positions) (7). The in situ spectrum (Fig.…”

Mössbauer investigation of the reaction between HCl and tin dopant ions located on the surface of Cr2O3 microcrystals

“…As to the anionic environment, it is similar for both sites and involves three oxygen atoms of the matrix surface, the lone electron pair of Sn(II) being perpendicular to this oxygen triangle. 2 The spectrum recorded after admitting HC1 ( the nearest surrounding. This is evidenced by the increased 8 values, as compared to those concerning initial (oxygen surrounded) Sn(II)-sites (81 = 2.81 mm/s and 82=2.91 mm/s), 2 which now fall into the isomer shift region of stannous chloride compounds.…”