Gibbs Free Energy of Formation of Eu1+yBa2−yCu3O7−xand Related Phases in the Eu2O3–CuO–BaO System

Gibbs Free Energy of Formation ofLn2CuBaO5Compounds Determined by the EMF Method (Ln=Yb, Tm, Er, Ho, Dy, and Gd)

“…CaF is a pure ionic conductor and the transport number of the fluoride ion in calcium fluoride is known to be unity. The cell construction in this study followed that used by Alcock and Li (10), and was identical with that used in our previous study (6). The cell assembly used in our work is schematically shown in Fig.…”

Gibbs Free Energy of Formation ofLnBa2Cu3O7−xPhases Determined by the EMF Method (Ln=Yb, Tm, Er, Ho, Dy)

“…Then, G can be calculated exactly from our EMF data under variable p O conditions. In the previous paper [9], we analyzed the literature data for the exchange reaction CaO#BaF "CaF #BaO [6] and have accepted the change in Gibbs free energy as given by Kaye and Laby (13), which is G ($1000 J)"63785!3.77 ) ¹. [7] Combining reaction [6] with reaction [3] gives the reaction 2¸n11232"¸n12112#5CuO#3BaO#(0.5!x)O [8] Finally, using Gibbs free energy change of the reaction of formation of respective¸n12112 phases from oxides determined in our previous work [11], one can derive the Gibbs free energy change of the reaction of formation of¸n11232 phases from respective oxides by adding the reactioņ errors in G shown in Table 1 were calculated using the formula…”

“…Our estimated enthalpy value for the Eu11232 phase falls in the similar ballpark: !163.3 kJ/mole (9). Recently, Lamberti et al (20) performed thermochemical investigations of compounds with¸n"Pr, Nd, Eu, Gd, Dy, Ho, and Tm and found that the enthalpies of formation of¸n11232 phases display essentially linear trend toward less exothermic values with increasing lanthanide atomic number, i.e., decreasing ionic radius.…”