tailieunhanh - Báo cáo hóa học: " The Periodic Instability of Diameter of ZnO Nanowires via a Self-oscillatory Mechanism"

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: The Periodic Instability of Diameter of ZnO Nanowires via a Self-oscillatory Mechanism | Nanoscale Res Lett 2007 2 492-495 DOI S11671-007-9094-0 NANO PERSPECTIVES The Periodic Instability of Diameter of ZnO Nanowires via a Self-oscillatory Mechanism Ye Zhang Youguo Yan Feng Zhu Received 17 August 2007 Accepted 30 August 2007 Published online 13 September 2007 to the authors 2007 Abstract ZnO nanowires with a periodic instability of diameter were successfully prepared by a thermal physical vapor deposition method. The morphology of ZnO nanowires was investigated by SEM. SEM shows ZnO possess periodic bead-like structure. The instability only appears when the diameter of ZnO nanowires is small. The kinetics and mechanism of Instability was discussed at length. The appearance of the instability is due to negative feed-back mechanism under certain experimental conditions crystallization temperature vapor supersaturation etc . Keywords ZnO nanowire Negative feed-back mechanism Growth mechanism Physical vapor deposition Introduction Various unusual morphologies of whiskers and nanowires have been reported in past few years 1-9 . Since its discovery by Wagner and Ellis in 10 the vapor-liquid-solid VLS growth mechanism 10 has been used to explain the formation of the majority of vapor grown whiskers and nanowires. The typical morphology of whiskers and nanowires is that each whisker or nanowire terminates with a catalyst particle on its end. Sears also propose another growth model so-called vapor-solid VS mechanism 11 to explain the initialization of the one-dimensional growth of nanowire or whisker with a catalyst-free process as followings if the supersaturation is below the value required for the Y. Zhang H Y. Yan F. Zhu Key Laboratory of Materials Physics Institute of Solid State Physics Hefei Institutes of Physical Science Chinese Academy of Sciences Hefei 230031 . China e-mail yezhang@ formation of a crystal of some material with euhedral morphology anisotropic one-dimensional growth occurs in specific crystal directions. The .