Global ETD Search

1	Influence of defects on thermal and mechanical properties of metals Kamani, Sandeep Kumar 15 May 2009 (has links) The crystallization/freezing and melting phenomena are critical in processing of chemicals and materials. Although melting is a very fundamental problem, the mechanism behind it has not been completely answered satisfactorily. Hence its study becomes very important. Perfect crystals do not exist; therefore it is very important to include the effect of defects in the above mentioned processes. The purpose of this work is to employ molecular simulation to further extend the understanding of theories of melting with respect to defects. We studied the melting and freezing process for a model system of copper with and without defects. We studied point defects (1, 2, 4, 8 vacancies and 1, 2, 4, 8 interstitials), line defects (edge dislocation) and surface defects (grain boundary) using molecular dynamics simulations. Constant stress-constant temperature ensemble with atmospheric pressures is employed. Various properties like average volume, density, potential energy and total energy are obtained as a function of temperature for each system. Most of the properties vary linearly before and after the phase transitions. During the transition process they show a dramatic change. This change is a sign of phase transition. The phase transition temperatures obtained from the single phase simulations are not the true melting (or freezing) points as there is some amount of superheating (or supercooling). Coexistence phase simulations are also done for the case of copper with no defects to find the true melting point. Most of the literature dealing with melting/crystallization on the basis of atomistic simulation does not include the influence of the presence of defects. Thus this work has a bearing on the various theories of melting. defect melting
2	Electronic characteristics of defects of GaN films grown on Si(111) substrate Chen, Bo-Chih 28 July 2009 (has links) The electronic properties of the defects of the GaN/Si(111) system has been successfully measured by STM in the work. Different types of the dislocations in GaN films, such as edge dislocations and screw dislocations, have been observed. Defects induce the change of the band gap from 3.4 eV to 2.2 eV. The characteristic scattering length of the edge dislocation is around 25 nm. dislocation defect
3	Non-destructive testing of concrete piles using the sonic echo and transient shock methods Chan, Hon-Fung Cyril January 1987 (has links) No description available. 624.1 Pile defect testing
4	Studies of deep levels of semiconductors Nash, Keith James January 1987 (has links) No description available. 530.41 Semiconductor defect studies
5	Study of ion implantation damage in silicon wafers using phonons Strickland, Keith R. January 1992 (has links) No description available. 530.41 Defect in semiconductors
6	The infrared spectrum of molecular hydrogen Guest, Michael Arthur January 1989 (has links) No description available. 539.7 Quantum defect theory
7	Electron spin resonance studies of electron irradiated diamond Lea-Wilson, M. A. January 1988 (has links) No description available. 530.41 Diamond defect analysis
8	A clinical and molecular genetic study of dominant optic atrophy mapping to chromosome 3Q28-qter Votruba, Marcela January 2000 (has links) No description available. 610 Eye defect genetics
9	An optical study of defects in diamond Beard, D. R. January 1987 (has links) No description available. 530.41 Diamond defect study
10	Product liability in the vehicle manufacturing industry : The history and development of product liability in the USA, Europe and the UK and its effect in particular on a commercial vehicle manufacturer Farnworth, N. R. January 1987 (has links) No description available. 629.049 Vehicle defect liability

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