A study of the mass transport properties of the solid state copper(I) ion conductor Rb 4Cu 16I 7Cl 13 and its application in the determination of the thermodynamic stability of Nd 2CuO 4

Abstract

The preparation of Rb 4 Cu 16 I 7 Cl 13 from the respective metal halides in flowing argon is described. The electrochemical behavior of the solid state cell Cu|Rb 4 Cu 16 I 7 Cl 13 |Cu has been studied by impedance spectroscopy. The electronic resistance of the external circuit is significant and is taken into consideration in the evaluation of the ionic conductivity. Rb 4 Cu 16 I 7 Cl 13 has a copper ion conductivity of 69 Sm −1 at 473 K, and an activation energy of 14 kJ mole −1 in the temperature range 351 to 473 K. Titration of copper through the cell revealed interesting morphological features of copper crystal growth at 473 K. EMF measurements on the cell Cu|Rb 4 Cu 16 I 7 Cl 13 |Nd 2 CuO 4 , Nd 2 O 3 , O 2 , Pt gave δ G o =−27,300 −61 T J mole −1 K −1 for the cell reaction Cu(c)+0.5 O 2 (g)+Nd 2 O 3 (c)=Nd 2 CuO 4 (c).