Dislocation-assisted-diffusion model for the kinetics of bismuth cuprate 2212-to-2223 transformation

Recent transmission electron microscopy (TEM) experiments have shown that the transformation of the Bi cuprate 2212 phase to 2223 phase consists of random intercalation and fast growth of Ca/CuO/sub 2/ planes in the Bi-2212 matrix. This contradicts the prediction of the conventional nucleation and growth theory. A model is proposed which considers the cylindrical void created by the edge dislocation due to the insertion of a Ca/CuO/sub 2/ plane to be a channel for fast ion diffusion. The experimentally observed time dependence of the volume fraction of Bi-2223 during the transformation is found to be consistent with a one-dimensional diffusion-controlled transformation mechanism, as predicted by our model. The formation energy of Bi-2223 is estimated and is consistent with the results of atomistic simulations.