Particle motions in superionic conductors

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Abstract
The motion of ions in Ca2+F2− has been studied by molecular dynamics. The results show that, at 2.525 g cm−3 and 1590 K, the F−’s have a constant of self‐diffusion of 2.6×10−5 cm2 sec−1 and the Ca2+’s form a stable lattice. It is found that half of the F−’s occupy the octahedral sites of the fcc Ca2+ lattice. The details of the self‐diffusion process is analyzed showing the presence of a wave‐vector dependent long relaxation time in the decay of 〈exp(ik⋅u(t) 〉, which is the Fourier transform of the displacement u(t) of the F− ions.