Framework solid electrolytes can be thought of as a sublattice of mobile ions diffusing through a vibrating covalent counterion framework. A crucial question in the physics of such materials is then to determine the effects of correlation among the diffusing ions on the structural properties of the mobile sublattice. To investigate structural implications of correlation among the diffusing ions, we have calculated the static structure factor S(q) = (1/N) ∑ij〈eiq(xi-xj)〉, which gives information about the distribution of the mobile ions over the periodic potential. All computations are performed using Langevin dynamics to simulate Brownian motion of the ions in the periodic framework potential. By fitting S(q) to the experimental results of potassium hollandite, in which the ions are confined to move in a linear channel, we extract the values of the pair potential and the barrier height of the framework potential. We also compute S(q) using the homogeneous approximation (g(x,x′) ≃ g0(x-x′)). By comparing the result to the exact one obtained from numerical simulation, we are able to draw conclusions about the validity of the homogeneous approximation.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry