Papers by Author: M. Čančarević

Abstract: One of the methods for powder synthesis that is both cost and time effective is the selfpropagating room temperature synthesis. We applied this method to synthesize rare earth doped ceria nanopowders. Since they exhibit very high ionic conductivity at intermediate temperatures these compositions are attractive for a new generation of nanostructured ceramics applicable in solid oxide fuel cells as electrolytes. In this paper we paid our attention to the reaction based on methathetical pathway, whereby solid solution nanopowders of rare earth elements with ceria were obtained at room temperature. Compositions of Ce1-xRexO2-δ (Re = Y , Nd) were synthesized with x ranging from 0 to 0.20. The reaction course is discussed and the properties of the obtained powders are presented.

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.