Standard enthalpies of formation of yttrium gallides by high temperature reaction calorimetry

2000 ◽  
Vol 311 (2) ◽  
pp. 200-206 ◽  
Author(s):  
R Babu ◽  
K Nagarajan ◽  
V Venugopal
Keyword(s):  
High Temperature ◽  
Enthalpies Of Formation ◽  
Reaction Calorimetry ◽  
Temperature Reaction ◽  
High Temperature Reaction ◽  
Standard Enthalpies Of Formation

Thermochemistry of the Y2O3–BaO–Cu–O system

1992 ◽  
Vol 7 (11) ◽  
pp. 2920-2935 ◽  
Author(s):  
Zhigang Zhou ◽  
Alexandra Navrotsky
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Enthalpies Of Formation ◽  
Reaction Calorimetry ◽  
Lead Borate ◽  
Temperature Reaction ◽  
Thermodynamic Relationships ◽  
High Temperature Reaction ◽  
Molten Lead

High temperature reaction calorimetry using molten lead borate as a solvent is used to study the thermochemistry of phases in the Y2O3–BaO–Cu–O system. Enthalpies of formation of YBa2Cu3Ox (6 < x < 7), YBa2Cu4O8, Y2BaCuO5, Y2Cu2O5, and BaCuO2.01 phases have been determined. The thermodynamic relationships among these phases at room temperature have been assessed. The results show that the 123 phase is not thermodynamically stable with respect to assemblages containing combinations of Y2BaCuO5, Y2Cu2O5, BaCuO2, Y2O3, and CuO. The fully oxidized 123 phase is not stable with respect to the 124 and the above assemblages. Reactions at room temperature are shown as follows: YBa2Cu3O7 (s) + CuO (s) → YBa2Cu4O8 (s); δH = −31.9 ± 22.3 kJ mol−1 and YBa2Cu3O6.76 (s) → ½YBa2Cu4O8 (s) + ¼Y2BaCuO5 (s) + ¾BaCuO2.01 (s); δH = −78.9 ± 21.0 kJ mol−1.

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