Electrochemical Variation of HTSC Stoichiometry

La2Cu04 (LCO) is a dielectric, the doping of which with oxygen leads to metallization accompanied by transition to the superconducting state at sufficiently low temperatures [250]. The value of 7c achieved by this method of synthesis correlates with the value of 6 (the greatest observed Tc values are 40-45 K). 

LCO has been actively studied as a model system for elucidating the nature of the superconduction phenomenon in cuprate systems because of the relative simplicity of its chemical composition and structure. The HTSC studies of the effects of oxygen 

Stoichiometry and the resulting phenomenon of phase separation represent a good example of the achievements of modem electrochemistry of HTSCs [239,240]. 

It is from experiments on electrochemical doping that the LCO phase diagram was obtained. The problem of equilibrium establishment in the oxygen sublattice of nonstoichiometric cuprates is closely related to the nature of excess oxygen species in the solid phase and, in turn, the preferential diffusion paths in the lattice, and the diffusion kinetics. 

These authors assume that lattice incorporation occurs with the participation of metal ions 

---