Electrochemical intercalation of oxygen in lanthanum copper oxide at ambient temperature

Abstract

The electrochemical intercalation of La 2CuO 4 at ambient temperature has been investigated. Galvanostatic and potential step experiments show that the oxygen atoms intercalated on oxidation are completely removed on reduction. The voltage composition profiles observed on oxidation and reduction, however, are very different and equilibrium is not attained. In particular the results obtained on reduction show clear evidence for a nucleation controlled phase separation. Samples prepared electrochemically show superconducting transitions with onset temperatures of ∼30 K and ∼42K depending on the oxygen content, in agreement with previous results. The electrochemical and T c data are discussed in relation to the proposed ambient temperature phase diagram of La 2CuO 4+x.