Local Structural Disorder and Relaxation in SnO₂ Nanostructures Studied by ¹¹⁹Sn MAS NMR and ¹¹⁹Sn Mössbauer Spectroscopy

Abstract

We studied the local structural disorder and relaxation in different nanostructures of SnO2 by using 119Sn MAS NMR in combination with 119Sn Mössbauer spectroscopy. We investigated nanocrystalline powders with an average crystallite size of 8 nm as well as hollow spheres with a wall thickness of 3 nm and a diameter of 14 nm, and compared the results to coarse-grained materials. Whereas the uniform SnO6 octahedra in the coarse-grained material show a well-known distortion and thus large electric field gradients, the nanocrystalline SnO2 exhibits a structural relaxation leading to a distribution of local environments and more symmetric octahedra. The SnO2 hollow spheres show strong local disorder in combination with highly asymmetric environments around the Sn atoms.

Unravelling the mechanism of lithium insertion into and extraction from trirutile-type LiNiFeF6 cathode material for Li-ion batteries

“…9 shows the 7 Li MAS NMR spectra of LiNiFeF 6 directly after synthesis, after milling with PVdF binder and carbon, These broad peaks may be caused by Li ions located on the 4e sites and also by the Fe/Ni cation disorder on the transition metal sites around the Li ions. 57 A small, narrow contribution at 0 ppm also reveals that milling induces the formation of a diamagnetic phase, probably a small amount of LiF. After milling of the LiNiFeF 6 together with PVdF and carbon, a similar 7 Li NMR spectrum is obtained, but the broad components show further broadening revealing an increase in structural disorder, i.e.…”

Nonequilibrium structure of Zn2SnO4 spinel nanoparticles

“…As it is clearly demonstrated in our work on the mechanosynthesis of ternary complex oxides, 14,[17][18][19] solely from the XRD measurements, it is not clear whether the mechanochemical processing of a mixture of reaction precursors leads to the complete conversion to a complex oxide, even if the diffraction patterns of the milled powders exhibit typical features of a desired phase. According to our experience, 14,[17][18][19][20][21][22] the simultaneous use of diffraction techniques, which are sensitive to medium-and long-range structural order, and spectroscopic techniques such as nuclear magnetic resonance (NMR), Raman spectroscopy and/or M€ ossbauer spectroscopy, which make possible observations on a local atomic scale, is indispensable in many cases to allow for a comprehensive characterization of the product of a mechanochemical reaction.…”

Insights into the Nature of the Active Sites of Tin‐Montmorillonite for the Synthesis of Polyoxymethylene Dimethyl Ethers (OME)

“…No tetrahedral tin was detected. Variation of the main peak can be the result of hydroxylation of SnO 2 surface and its crystalline size . Peak broadening indicates the presence of SnO 2 nanocrystals as surface atoms have different chemical shifts compared to bulk atoms.…”

“…Variation of the main peak can be the result of hydroxylation of SnO 2 surface and its crystalline size. [50] Peak broadening indicates the presence of SnO 2 nanocrystals as surface atoms have different chemical shifts compared to bulk atoms. Hydroxylation of the tin surface was indicated by signals of the first and second tin layer which have chemical shifts of À 590 and À 615 ppm, respectively (Figure 6a, inset).…”