Optimal Zn/O ratio in vapor phase for the synthesis of high quality ZnO tetrapod nanocrystals via thermal evaporation of Zn in Air

• Published in: Applied surface science Vol. 259; pp. 562 - 565
• Main Author: Lee, Geun-Hyoung
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.10.2012; Elsevier
• Subjects: Air atmosphere; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Evaporation; Exact sciences and technology; Nanocrystals; Optimization; Physics; Synthesis; Thermal evaporation; Ultraviolet emission; Vapor phases; Zinc; Zinc oxide; Zn powder; Zn/O ratio; ZnO tetrapod; Air atmosphere; Zn/O ratio; ZnO tetrapod; Zn powder; Thermal evaporation; Inorganic compounds; Transition element compounds; Zinc oxide; Nanocrystal
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2012.04.183

► Tetrapod ZnO nanocrystals were synthesized through thermal evaporation of Zn in air. ► There is an optimal Zn/O ratio required for the synthesis of tetrapod ZnO nanocrystals. ► Zn/O ratio in vapor phase had an effect on the optical properties of tetrapod ZnO nanocrystals. Tetrapod-shaped ZnO nanocrystals were synthezised via thermal evaporation of Zn powder in air. The Zn powder was oxidized at 930°C for 60min. To investigate the optimal Zn/O molar ratio in such vapor phase synthesis, the Zn content was varied in range of 0.1–0.75g. When the Zn content was 0.1g, no nanocrystals were formed. Above 0.25g Zn, growth of ZnO nanocrystals started without clear tetrapod like morphology. Beyond Zn content of 0.50g, clear tetrapod-shaped ZnO nanocrystals were detected. These results establish that there is a certain required ratio of zinc and oxygen in vapor phase for generation of tetrapod-shaped ZnO nanocrystals. Such Zn:O ratio is also calculated theoretically from the ideal gas law. Clear tetrapod type ZnO nanocrystals prepared with Zn content of 0.5g exhibited the highest intensity of the ultraviolet emission centered at 380nm which also confirms the high crystalline quality of such ZnO nanocrystals.