Transmission Electron Miscroscopy Observation of the Decomposition of YBa₂Cu₄O₈ into YBa₂Cu₃O_7-δ and CuO

Abstract

The decomposition of YBa 2 Cu 4 O 8 (Y-124) into YBa 2 Cu 3 O 72d (Y-123) and CuO at high temperatures has been expected to create Y-123 with finely dispersed CuO precipitates suitable for flux pinning. In fact, samples of thermally decomposed Y-124 exhibit a critical current density, J c , which is enhanced with respect to the starting material as well as to pure Y-123. Transmission electron microscopy (TEM) studies of furnace annealed Y-124 were not suitable to clarify the reason for this J c enhancement. Nevertheless, the formation and growth of CuO precipitates have been observed by in situ decomposition of the Y-124 starting material due to electron beam heating within the TEM. 906

Significant improvement of the critical current of MOD-derived YBa2Cu3O7-δ -coated conductors by post-annealing treatment

“…The Y124 and Y247 phases are unstable at high temperatures in a very thin P O2 atmosphere. 21,24,25) The present post-annealing treatment is very facile to implement for long industrial MOD-RE123 tapes (as long as 500 meters). As shown in Fig.…”