EFFECT OF PREPARATION ON HG-BA-CA-CU-O SUPERCONDUCTORS

Some main features of the non-linear synthesis process are described b y theoretical considerations. Results of typical preparation methods a re compared to each other and to those obtained by the experiments des igned specially for the study of the effect of synthesis on the superc onducting properties of Hg-Ba-Ca-Cu-O compounds. As is shown, the cont rolled Hg-vapour pressure method, the sealed tube with phase formation procedure, the high-pressure synthesis and the freeze-drying method s eem to be unambiguously reliable to provide high-quality samples. Sign ificant deviations from these fundamental synthesis routes can lead to significant deviations of superconducting parameters.