Estimation and revision of some thermodynamic data in the YBaCuO system. Part 2. Standard entropies of formation

Abstract

From a review of the literature data, we have estimated the basic standard entropies of formation from the elements S̄ ⊖ 298 of YBa 2Cu 3O 7 (123-O 7), YBa 2Cu 3O 6 (123-O 6), YBa 2Cu 4O 8 (124-O 8), YBa 2Cu 3.5O 7.5 (123.5-O 7.5), YCuO 2 (101) and Y 2Cu 2O 5 (202). It is shown that for the S ⊖ 298(i) estimation, it is better to use the method of increments of the ions constituting the compound, rather than the method of addition of standard entropies of the simple oxides forming the compound. In addition, S ⊖ 298 values were calculated for YBa 2Cu 5O 9 (125-O 9), YBa 4Cu 3O 8.5 (143-O 8.5), BaCuO 2 (011), BaCu 2O 2 (012), Ba 2CuO 3 (021), Ba 3CuO 4 (031), Y 2BaCuO 5 (211), Y 2BaO 4 (210), Y 2Ba 4O 7 (240) and Y 2Ba 2O 5 (220).