tailieunhanh - Báo cáo hóa học: " Investigation of Nucleation Mechanism and Tapering Observed in ZnO Nanowire Growth by Carbothermal Reduction Technique"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Investigation of Nucleation Mechanism and Tapering Observed in ZnO Nanowire Growth by Carbothermal Reduction Technique | Kar et al. Nanoscale Res Lett 2011 6 3 http content 6 1 3 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access Investigation of Nucleation Mechanism and Tapering Observed in ZnO Nanowire Growth by Carbothermal Reduction Technique 14 5 1 2 3 I 2 4 5 Ayan Kai Ke Din Low Michael oye Michael A Dtiusciu Mitia Dutta Alan iNici lolls M ivieyyappan Abstract ZnO nanowire nucleation mechanism and initial stages of nanowire growth using the carbothermal reduction technique are studied confirming the involvement of the catalyst at the tip in the growth process. Role of the Au catalyst is further confirmed when the tapering observed in the nanowires can be explained by the change in the shape of the catalyst causing a variation of the contact area at the liquid-solid interface of the nanowires. The rate of decrease in nanowire diameter with length on the average is found to be nm s and this rate is larger near the base. Variation in the ZnO nanowire diameter with length is further explained on the basis of the rate at which Zn atoms are supplied as well as the droplet stability at the high flow rates and temperature. Further saw-tooth faceting is noticed in tapered nanowires and the formation is analyzed crystallographically. Introduction Interest in nanowires continues to grow fueled by applications in electronics optoelectronics sensors piezoelectric and thermoelectric devices and energy storage 1 . In spite of considerable advances in growth and application development of nanowires the various proposed growth mechanisms are still controversial and subject to immense discussion. For example it is well documented that the diameter of nanowires grown via the vapor-liquid-solid VLS mechanism is determined by the size of the droplet. This is true but it does not necessarily imply that the diameter of nanowires is constant along its axis. It has been recently reported that the dynamic reshaping of the catalyst particles during