Nonequilibrium structure of Zn2SnO4 spinel nanoparticles

Zinc stannate (Zn2SnO4) nanoparticles with an average size of about 26 nm are synthesized via single-step mechanochemical processing of binary oxide precursors (ZnO and SnO2) at ambient temperature, without the need for the subsequent calcination, thus making the synthesis route very simple and cost-effective. The mechanically induced phase evolution of the 2ZnO + SnO2 mixture is followed by XRD and by a variety of spectroscopic techniques including 119Sn MAS NMR, Raman spectroscopy, 119Sn Mössbauer spectroscopy, and XPS. High-resolution TEM studies reveal a non-uniform structure of mechanosynthesized Zn2SnO4 nanoparticles consisting of a crystalline core surrounded by a structurally disordered surface shell. Due to the ability of the applied solid-state spectroscopies to probe the local environment of Sn cations, valuable complementary insight into the nature of the local structural disorder of mechanosynthesized Zn2SnO4 is obtained. The findings hint at a highly nonequilibrium state of the as-prepared stannate characterized by its partly inverse spinel structure and the presence of deformed polyhedra in the surface shell of nanoparticles.