Enthalpy of Formation of Cu2PbO2 and Revision of the Cu2O-PbO Phase Diagram |
| Journal |
Materials Science Forum (Volume 494) |
| Volume |
Current Research in Advanced Materials and Processes |
| Edited by |
Dragan P. Uskokovic, Slobodan K. Milonjic, Djan I. Rakovic |
| Pages |
67-72 |
| DOI |
10.4028/www.scientific.net/MSF.494.67 |
| Online since |
September, 2005 |
| Authors |
M. Čančarević,
Matvei Zinkevich,
Fritz Aldinger
|
| Keywords |
Cu2O-PbO Phase Diagram, Cu2PbO2, Enthalpy |
| Abstract |
The stoichiometric compound Cu2PbO2 has been synthesized by solid-state reaction from Cu2O and PbO in a sealed quartz ampoule. The optimum synthesis conditions are 910 K and 260 h. The enthalpy of formation of Cu2PbO2 has been measured with the use of high-temperature calorimeter. The enthalpy of reaction Cu2O + PbO = Cu2PbO2 is – 25.4 ± 1 kJ·mol-1 at temperature 968 ± 5 K. Standard enthalpy and Gibbs energy of formation of the Cu2PbO2 compound from elements and its entropy at 298.15 K are DfH° = – 413.086 kJ·mol-1, DfG° = – 353.165 kJ·mol-1 and S° = 135.165 J·mol-1·K-1. The eutectic reaction L → Cu2O + PbO was found to occur at 1017 ± 5 K. Using the thermodynamic database for Cu-Pb-O system the revised Cu2O-PbO phase diagram is proposed. |
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