奈米材料相變研究

材料模擬實驗方法由於受限於尺度效應等關係,不同尺度下無法藉由單一套的統馭方程式描述,因此通常區分為微觀、介觀、與巨觀的模擬系統,其中在微觀模擬的分子動力學(MD)方法上系統僅能模擬短時間與小系統,過去儘管高速電腦迅速發展,模擬尺寸已可匹配產業界的製程尺寸,但模擬時間問題上,因礙於描述分子的各種物理量,必須考慮原子震動行為,因此模擬時間步階需小到飛秒(femtosecond),也因此在模擬與時域相依特性之問題時,MD在時間域的問題仍舊為人所詬病。近年來本人已成功開發Parallel replica dynamics (PRD)加速分子動力學,此技術可令MD模擬時間步階達到微秒級數,並實現實驗所觀察之研究現象,由本人今年的研究中,已成功利用PRD模擬晶體金奈米線之相變化過程,由晶體FCC結構變化成螺旋層狀結構,並觀察發現其相變過程,是伴隨著shear like transformation, dissociation, vacancy diffusion, dislocation, and twist deformation等多項機制的演變,最後才得以產生完美螺旋奈米線結構。


Publication: 
1. Wan-Sheng Su, Hsin-Tsung Chen, Jee-Gong Chang, Yeng-Tseng Wang, Wen-Jay Lee (2014, Feb). Investigation into the formation of 13-6 helical multi-shell gold nanowires. Computational Materials Science, 82, 226-230 . (SCI, N/M=72/241 MATERIALS SCIENCE, MULTIDISCIPLINARY). NSC 102-2218-E-492-002. 

2. Wen-Jay Lee, Chun-Wei Pao, Jee-Gong Chang (2012, Dec). Diffusion of the vacancy defect leading the formation of a Perfect Multi-Shell structures in the nanobridge. Journal of Applied Physics, 112(11), 114301. (SCI, 37/125,
PHYSICS, APPLIED). NSC 100-2221-E-492-019. 

3. Wen-Jay Lee, Chun-Wei Pao and Jee-Gong Chang (2012, Sep). Helical multishell structures in gold nanobridge and suspending nanowire. Journal of Nanoparticle Research, 14, 1058. (SCI, 38/232, MATERIALS SCIENCE, MULTIDISCIPLINARY; 36/154, CHEMISTRY, MULTIDISCIPLINARY; 24/66,NANOSCIENCE & NANOTECHNOLOGY). NSC 100-2221-E-492-019.