(403d) Flame Synthesis of Doped Zno Nanorods

Mädler, L., University of Bremen IWT Foundation Institute of Materials Science
Pratsinis, S. E., Swiss Federal Institute of Technology, Particle Technology Laboratory, ETH Zurich

Nanorods are nanoscale particles with an aspect-ratio (ratio of length to diameter) greater than unity and a dominant linear, 1-dimensional geometry. Depending on the material composition, nanorods may exhibit unique electronic, optical and mechanical properties that appeal to a range of applications including electronics, sensors, optical components and displays, polymer-composites, and actuator devices. Synthesis of nanorods is typically carried out via vapour-phase (eg. evaporation/condensation) or wet-chemistry (eg. solvothermal) routes. Despite being capable of producing well-controlled material uniformity and properties, these techniques are limited in their scale-up potential. In this work we report the flame-aerosol synthesis of doped zinc-oxide nanorods with closely controlled aspect ratio. Zinc-oxide nanorods doped with indium, tin or lithium dopant species at concentrations up to 10 at.% preserve the single-phase ZnO wurtzite structure. In and Sn dopants alter the shape of the ZnO particles, inducing a rod-like geometry with increasing dopant concentration. The aspect ratio for both the In- and Sn-doped ZnO crystals increased by a factor of 5 from 0.6 to over 3 as dopant was increased up to 10 at.% as measured by X-ray diffraction (XRD). This was confirmed by transmission electron microscopy (TEM), indicating a prevalence of nanorod structures with increasing dopant concentration. This work demonstrates the synthesis of nanorods unambiguously in the vapour-phase in contrast to tubular-reactor type methods and provides an efficient route to scale-up of a novel nanorod material.