Pressing condition effect on structure and superconducting properties of YBaCuO ceramics

A study was made on correlations of superconducting and structural parameters of HTSC samples after cold and hot pressing with successive heat treatment. It was established that those parameters changed consistently during thermomechanical treatment of YBaCuO ceramics; Tc(c) dependence couldn't be explained at that by change of oxygen concentration. HTSC properties under mentioned conditions are affected mainly by planar defects in 1-2-3 structure, which occur due to plastic strain of ceramics under pressing. These defects are not completely annealed during heat treatment. Loading rate under pressing is more critical parameter, as compared to pressing force. Partial decomposition of 1-2-3 phase takes place under hot pressing besides defect accumulation. Stepwise loading with heat treatment at each loading stage should be conducted in order to improve HTSC properties during thermomechanical treatment