HIGH-TEMPERATURE HEAT CAPACITIES OF THE PHASES IN Y-Ba-Cu-O SYSTEM

ＨＩＧＨ－ＴＥＭＰＥＲＡＴＵＲＥＨＥＡＴＣＡＰＡＣＩＴＩＥＳＯＦＴＨＥＰＨＡＳＥＳＩＮＹ－Ｂａ－Ｃｕ－ＯＳＹＳＴＥＭＺｈａｎｇＨｅｎｇｚｈｏｎｇ；ＦａｎｇＺｈｅｎｇ；ＺｈａｎｇＰｉｎｇｍｉｎ；ＣｈｅｎＸｉｎｍｉｎ（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｅｍｉｓ...

TG and DSC techniques were used to investigate the phases and the reaction behavior at elevated temperatures of the oxygen-nonstoichiometric compounds YBa2Cu3O7-x and BaCuO2+z. Based on the results of TG and DSC experiments, appropriate procedures were found for heat capacity measurements of the phases with DSC method. Combined with the drop method, the heal capacities of the phases YBa2Cu3O6.90, Y2Cu2O5, Y2BaCuO5 and BaCuO2.42 were measured from room temperature to 973 K. The results for these phases are represented respectively as follows: C-p(J/mol . K) = 333.97 - 454.43 X 10(-3) T + 41.836 X 10(5) T-2 + 794.18 X 10(-6) T-2 C-p(J/mol . K) = 149.82 + 113.02 X 10(-3)T C-p(J/mol . K) = 329.09 - 361.56 X 10(-3) T - 42.745 X 10(5) T-2 + 341.43 X 10(-6) T-2 C-p(J/mol . K) = 77.628 - 14.018 X 10(-3) T + 18.141 X 10(5) T-2 + 130.85 X 10(-6) T-2.