SYNTHESIS AND THERMOCHEMICAL STUDY OF 1 2/4-PHASES IN THE (Y,GD)-BA-CU-O SYSTEM/

Synthesis of the YxGd1-xBa2Cu4O8 phases (x=1; 0.5; 0.75) by special me thod from nitrates is described in this paper. Dissolution enthalpies of YBa2Cu4O8, Y0.5Gd0.5Ba2Cu4O8, Y0.75Gd0.25Ba2Cu4O8, Y2O3, Gd2O3, CuO , BaCO3 were measured in 6 N HCl at 323 K. On the basis of obtained ex perimental data, the enthalpies of some reactions with YxGd1-xBa2Cu4O8 were determined. It was established that the above-mentioned 1:2:4 su perconductors were thermodynamically more favourable than mixtures inc luding CuO, YBa2Cu3Ox. It was also established that, according to the obtained data, these phases can react with CO2. (C) 1998 Elsevier Scie nce B.V.