Structural properties of supercooled liquid silicon by molecular dynamics (original) (raw)
Sign up to get access to over 50M papers
Sign up for access to the world's latest research
Related papers
Structure factor and atomic dynamics of stable and supercooled liquid silicon by molecular dynamics
Journal of Non-Crystalline Solids, 2002
The structural properties and the atomic dynamics of liquid and supercooled silicon are investigated by a molecular dynamics simulation, using the empirical Stillinger-Weber (SW) potential. The description of the structure factor is in good agreement with very recent X-ray diffraction experiments, provided that the SW model is modified by taking into account new experimental results of the density in the stable liquid near the melting point. The features of the velocity autocorrelation function and the corresponding spectral density are examined. The SW potential appears to be welldesigned for studying disordered phases of silicon. In particular, it allows us to investigate the process giving rise to the supercooled states, which are associated to a gradual increase of the density as confirmed by recent experiments.
Physical Review B, 1999
Constant-volume and constant-temperature molecular dynamics simulations have been performed to study the inherent structural properties of liquid silicon (l-Si) at different temperatures by using Tersoff potential. Our results first show that the 50°-60°peak in bond angle distributions decomposes into two peaks, which are located 52°and 60°, and a new peak at 75°appears; the 52°peak disappears with a small cutoff distance. The bond length of bonds contributing to 52°peak is much greater than the cutoff distance of covalent bond. The height of 52°peak at first increases and then decreases with temperature, and has a maximum at a certain temperature. The probability of the covalent bonds whose bond angle is greater than 67°shows an anomalous decrease at a certain temperature. These anomalous features may play an important role on the anomalous behavior of some physical properties in l-Si such as electrical resistivity. The height of 60°and 75°peaks increases with temperature.
Dynamic transitions in molecular dynamics simulations of supercooled silicon
Physical Review B, 2013
Two dynamic transitions or crossovers, one at a low temperature (T * ≈ 1006 K) and the other at a high temperature (T 0 ≈ 1384 K), are shown to emerge in supercooled liquid silicon using molecular dynamics simulations. The high-temperature transition (T 0 ) marks the decoupling of stress, density, and energy relaxation mechanisms. At the low-temperature transition (T * ), depending on the cooling rate, supercooled silicon can either undergo a high-density-liquid to low-density-liquid (HDL-LDL) phase transition or experience an HDL-HDL crossover. Dynamically heterogeneous domains that emerge with supercooling become prominent across the HDL-HDL transition at 1006 K, with well-separated mobile and immobile regions. Interestingly, across the HDL-LDL transition, the most mobile atoms form large prominent aggregates while the least mobile atoms get spatially dispersed akin to that in a crystalline state. The attendant partial return to spatial uniformity with the HDL-LDL phase transition indicates a dynamic mechanism for relieving the frustration in supercooled states.
Structural relaxation process in pure amorphous silicon
2015
Except where acknowledged in the customary manner, the material presented in this thesis is, to the best of my knowledge, original and has not been submitted in whole or part for a degree in any university. iii Williams, for generously providing scientific feedback on the research, while still permitting me to continuously improve my skills and allowing the progressive development of my autonomy. I also thank them for their persistent support, and for being gifted with a firm enthusiasm and a solid optimism which really helped to transform even the hard work into an enjoyable experience. I am really indebted for being given an invaluable contribution to this work and, even more, to my formation as a young researcher. It is a pleasure to work with Dr. Bianca Haberl. I thank her for her outstanding ability to suggest, and provide useful inputs for the possible directions in this research work. I am grateful for having her closely following my research, thus allowing me to benefit from her very extensive experience and knowledge. I thank Dr. Simon Ruffell, who had been exceedingly generous in sharing his time in plenty to stimulate scientific discussions during my first frustrating year as a student. This research is also not possible without many sources of practical and technical assistance and so I would like to express my sincerest gratitude to Dr. Brett Johnson from the University of Melbourne. Dr. Kidane Belay, who has always been exceedingly generous in sharing his time in plenty on ion beam discussions, and whose experimental support has been always at hand. Dr. Helmut Karl from the Universität of Augsburg, Germany for the use of secondary ion mass spectroscopy (SIMS). Alana Treasure from the University of Canberra for the use of Raman system. The indentation group for making it such an enjoyable group to conduct research in. I wish to spend also a few words on the colleagues who have shared with me the PhD experience. I thank Lachlan Smillie who offered me very detailed and useful comments, suggestions, and corrections on the thesis and Wenjie Yang for carefully proofreading my English. Sherman Wong for the lithography process. Many thanks to
Polymorphism in glassy silicon: Inherited from liquid-liquid phase transition in supercooled liquid
Combining molecular dynamics (MD) simulation and Voronoi polyhedral analyses, we discussed the microstructure evolution in liquid and glassy silicon during cooling by focusing on the fraction of various clusters. Liquid-liquid phase transition (LLPT) is detected in supercooled liquid silicon However, freezing the high-density liquid (HDL) to the glassy state is not achieved as the quenching rate goes up to 10 14 K/s. The polyamorphism in glassy silicon is found to be mainly associated with low-density liquid (LDL).
Loading Preview
Sorry, preview is currently unavailable. You can download the paper by clicking the button above.