Growth of ternary oxide nanowires by gold-catalyzed vapor-phase evaporation

Zn2SnO4 nanowires and Zn2SnO4 diameter-modulated (DM) nanowires were successfully synthesized, accompanied by the formation of ZnO nanowires, via the thermal evaporation of a mixture of ZnO and SnO2 powders, using gold as a catalyst. Their morphologies and structures were characterized by scanning electron microscopy, X-ray spectroscopy, and high-resolution transmission electron microscopy. The ZnO nanowires were single crystalline, with an axis of [0110], which is different from the conventional [0001] orientation and might be determined by the vapor components involved in the reaction. Zn2SnO4 nanowires and Zn2SnO4 DM nanowires were single crystalline, with [302] and [111] growth directions, respectively. A vapor-liquid-solid (VLS) growth mechanism is proposed, to interpret the growth of nanowires in the experiment. In regard to the formation of Zn2SnO4 DM nanowires, we suggest that the disturbance of vapor concentration is a major factor that changes the size of the catalyst alloy droplets and the growth velocity of nanowires, and ultimately results in the diameter-modulated feature.