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.