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Title: Computer calculations of the static and diffusive properties of hydrogen in metals for comparison with neutron scattering and other experiments.
Author: Wilson, D. L. T.
ISNI:       0000 0001 3570 0881
Awarding Body: University of Birmingham
Current Institution: University of Birmingham
Date of Award: 1978
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Computer simulation of atomic diffusion on periodic lattices has been used to investigate the effects of correlated atom jumping on the incoherent quasielastic neutron scattering law. It is found that the resulting shape can no longer be described by a single Lorentzian for the f.c.c. lattice as is predicted by the Chudley-Elliottmodel but is instead a more complicated function. This is compared with an analytic treatment of the encounter model (i.e. diffusion in the vacancy limit) and this analysis is also extended to finite vacancy concentrations under certain assumptions. The computer model has been extended to allow for the possibility of interactions between the diffusing atoms and it is found that the major effect is to change the residence time T. The elastic diffuse coherent scattering can also be obtained from the program as well as the configurational entropy. An application of the program is made to the SOK transition in P1". Diffusion on the tetrahedral interstitial sites of the b.c.c. lattice using a site blocking model is also investigated and correlation factors are obtained. It is found that for site blocking the correlation factor can be very low and hence the corresponding scattering law can be markedly changed. Finally a calculation of the lattice distortions around an interstitial proton in the palladium lattice is presented using the method of lattice statistics and the resulti~g diffuse scattering is obtained. By combining this with the diffuse scattering arising from the ordering of the protons, a quantity which can be directly compared with experimental data can also be obtained.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available