Gibbs energy of formation of Cu 2R 2O 5 ( R = Dy, Ho, Er, Yb) from component oxides employing solid oxide electrochemical cells

Abstract

High temperature phase relations in the Cu-R-O (R = Dy, Ho, Er, Yb) ternary systems suggest that there exists only one ternary oxide, Cu 2R 2O 5( R = Dy, Ho, Er, Yb). One of the three phase fields in these systems which is of interest consists of Cu 2 O + R 2 O 3 + Cu 2 R 2 O 5. Chemical potential of oxygen for the co-existence of this three phase assemblage is measured between 1050–1325 K employing the solid-state electrochemical cell, (−)Pt/Cu 2O + R 2O 3 + Cu 2R 2O 5//(CaO)ZrO 2//O 2( P = 0.0212 MPa)/Pt(+) Gibbs energy of formation of Cu 2R 2O 5 from component oxides is obtained by combining the measured oxygen potential for Cu 2 O + R 2 O 3 + Cu 2 R 2 O 5 three phase equilibrium and Cu 2O + CuO from literature. Based on the present results, Gibbs energy of formation of Cu 2Tb 2O 5, Cu 2Tm 2O 5, Cu 2Tm 2O 5 and Cu 2Lu 2O 5 has been estimated.