The interplay of crystallization kinetics and morphology during the formation of SnO2 nanorods: snapshots of the crystallization from fast microwave reactions

A microwave-assisted reaction pathway to rutile SnO2 nanorods was investigated. The microwave-treatment significantly reduces the reaction time compared to standard hydro-/solvothermal techniques. By moving the overall process into a shorter time slot, the growth and crystal formation during the reaction could be monitored via snapshots by trapping the intermediates through quenching. To gain a better insight into the template-free growth of one-dimensional (1D) nanostructures, a parameter-dependent (various temperatures/pressures and times were investigated) study was carried out. For all materials, the phase purity and crystallite sizes were determined by X-ray powder diffraction (XRD). The growth-orientation and terminating crystal faces of the reaction intermediates were determined using (HR)-TEM measurements. A growth mechanism was proposed. The optical properties were studied by means of Raman and infrared spectroscopy.