Enthalpy of formation of Y2Ba4Cu7O14.916

Thermochemistry of Gd2BaCuO5 and LuBa2Cu3Ox

“…We also used another scheme of calorimetric reactions to calculate the standard formation enthalpy of LuBa 2 Cu 3 O x and to confirm the reliability of our data. The scheme is described in ref in detail for calculation of the formation enthalpy of Y 2 Ba 4 Cu 7 O x . In this case, the calorimetric cycle is based on using experimental data for solution enthalpies of rare earth metals, complex oxides, and literature data of formation enthalpies of BaCl 2 , CuCl 2 , H 2 O, and HCl taken from refs – .…”

“…In this case, the calorimetric cycle is based on using experimental data for solution enthalpies of rare earth metals, complex oxides, and literature data of formation enthalpies of BaCl 2 , CuCl 2 , H 2 O, and HCl taken from refs – . Calculation of Δ f H o (LuBa 2 Cu 3 O 6.92 , 298.15 K) on the basis of the cycle of ref with our data for solution enthalpies of Lu and LuBa 2 Cu 3 O 6.92 allows one to obtain Lu (s) + 3Cu (s) + 2Ba (s) + 3.46O 2 (g) = LuBa 2 Cu 3 O 6.92 (s) + Δ f H o Δ f .1em H o .25em (298.15 K) = −2690.6 ± 12.3 kJ/mol As we can see, we have good agreement for calculation of the same value [Δ f H o (LuBa 2 Cu 3 O 6.92 , 298.15 K)] using different thermochemical schemes. This testifies in favor of the reliability of our thermochemical data.…”

“…The measured enthalpies of dissolution were used for calculating the enthalpy of the reaction Gd 2 O 3 (s) + CuO (s) + BaCO 3 (s) ) Gd 2 BaCuO 5 (s) + CO 2 (g) (11) ∆ r H o (323.15K) ) +197.4 ( 5.9kJ/mol Literature data for the heat of reaction BaO + CO 2 ) BaCO 3 ; formation enthalpies of BaO, CuO, and Gd 2 O 3 ; and heat capacities 22 were used to calculate the enthalpy of formation of Gd 2 BaCuO 5 from binary oxides and standard formation enthalpy as follows:…”

“…However, there are some uncertainties regarding their thermochemistry. Thermochemical properties were investigated mainly for Y 2 O 3 −BaO−Cu−O, – and to a lesser extent for other RE 2 O 3 −BaO−Cu−O systems. , We determined the enthalpy of formation of GdBa 2 Cu 3 O x previously . There are no thermochemical data for Gd 2 BaCuO 5 and the superconductor LuBa 2 Cu 3 O x .…”