Abstract
In this study, a one-step approach is utilized to fabricate Au-SnO2 core-shell nanowires. 250 nm Au nanoparticles were dispersed on a Si substrate with 350 nm silica capping layer, Sn vapor was provided by Sn powders at elevated temperature. The crystal structure, microstructure, and the chemical composition of the as-grown products were examined by X-ray diffractometer (XRD), and field emission transmission electron microscopy (FETEM) attached with an energy dispersive spectrometer (EDS). To investigate the thermal behaviors of Au(Sn)-SnO2 core-shell nanowires, an in-situ TEM was used to observe the sequential reactions during the process of the nanowires. The Au(Sn) core has a thermal expansion coefficient of 1.02×10-4 (1/K), and the coefficient of thermal expansion of SnO2 shell is 5.9×10-6 (1/K) in the temperature region of 250-750℃. Hence, Au(Sn)-SnO2 core-shell nanowires can be good candidate of high temperature nanothermometers. On the other hand, a possible growth model of Au(Sn)-SnO2 core-shell nanowires can be proposed through the solid-liquid transition temperature of the Au(Sn) core and the Au-Sn binary phase diagram. The Au(Sn) core melted at the temperature region of 200-250℃, then the possible composition of the Au(Sn) core could be predicted by using the Au-Sn binary phase diagram. Finally, the exact composition of the Au(Sn) core were characterized by high resolution transmission electron microscopy (HRTEM).