A computer simulation study of lithium diffusion in the 123 and 124 superconductors

Atomistic computer modelling has been applied to the structure of the YBCO family of superconductors, and the diffusion profiles of Li+ ions through the barium channels. The calculated structures agree well with the experimental data for both the 123 and 124 structures. However a slight modification to the 124 structure is suggested which we believe is consistent with experimental evidence. The calculated activation energy for Li+ diffusion ∼0.8 eV in the 124 agrees well with experimental measurements. An hypothesis is suggested for the difficulty encountered in synthesising the 125 structure. (orig.)