Thermal Stability of ZnS Nanowires Studied by Using In-situ Heating X-ray Diffraction

The thermal stability of ZnS nanowires grown in a Au/Pd-mediated vapor-liquid-solid manner was studied by using an X-ray diffractrometer equipped with an in-situ heating system. Using an in-situ heating X-ray system, we monitored the structural degradation of ZnS nanowires in the temperature range from 25 ◦C to 900 ◦C. From the X-ray diffraction data recorded from 25 ◦C to 900 ◦C, the as-synthesized ZnS nanowires were identified to have a sphalerite structure at 250 ◦C and that initial structure was preserved up to 400 ◦C. Above 500 ◦C, a distinct sphalerite structure degradation was revealed, which is related to the disappearance of the (111) and the (200) peaks. Through the extended temperature region up to 900 ◦C, we found continuous reduction of the (111) and the (200) peaks. Especially, a pure Zn peak showed up at 700 ◦C, which can be considered to be due to a partial phase decomposition of ZnS nanowires. Further, we employed electron microscopes to observe the morphological and the structural changes corresponding to the initial and the final states of ZnS nanowire products.