Short range order in lattice dynamics and the feasibility of exafs measurements
Laaksonen, Reima Tapani
Wang, C. C.
Master of Arts
We studied theoretically the kinetics of a bcc lattice near the critical temperature. Our motivation is to examine the feasibility of using the recently developed time-resolved EXAFS technique to study the lattice dynamics. We derived the kinetic equations using the quasi-chemical approximation and keeping the number of particles constant and allowing only atom-vacancy exchange process. We solved these equations for a relaxation process following a sudden temperature change. Our calculations show that the long-range order exhibits critical slowing-down, as expected. Also the non-linear coupling between short- and long-range order was observed. Because of this non-linear coupling the relaxation of the short-range also slows down near the critical temperature. Our results put stringent conditions on possible experiments.