Thesis
Cadmium jump frequencies in L12 intermetallic compounds
Master of Science (MS), Washington State University
2008
Handle:
https://hdl.handle.net/2376/101596
Abstract
Perturbed angular correlation spectroscopy was applied to study atomic movement in L12 type rare earth indides, gallides and aluminides. Nuclear relaxations were measured as a function of temperature and were related to the jump frequencies of 111In/Cd tracers by the XYZ model. Activation enthalpies were obtained by fitting jump frequencies to the Arrhenius temperature dependence. Measurements were made on opposing phase boundaries of the indide phases and the jump frequency was found to be highly dependent on the composition of the samples. Higher jump frequency and lower activation enthalpy were observed at the more In-rich phase boundary for the early rare earth indides and at the less In-rich phase boundary for the late rare earth indides. This reversal of behavior strongly suggests the existence of different diffusion mechanisms. The behavior of the late rare earth indides can be explained by a simple monovacancy diffusion mechanism. Three mechanisms are discussed in order to explain the behavior of the early rare earth indides, among which the six jump cycle mechanism is decided to be the most feasible one. With the assumption of this mechanism, the differences between activation enthalpies for the opposing phase boundaries are attributed to formation enthalpies of rare earth vacancies.
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Details
- Title
- Cadmium jump frequencies in L12 intermetallic compounds
- Creators
- Xia Jiang
- Contributors
- Gary S. Collins (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Physics and Astronomy, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Identifiers
- 99900525128901842
- Language
- English
- Resource Type
- Thesis