ELECTROCHEMISTRY AND STAGING IN LA2CUO4+DELTA

Measurements:are reported of the time dependence of the current during electrochemical oxidation and reduction at a fixed voltage of single crystals and ceramic samples of La2CuO4+delta. Staging peaks in neutro n measurements of the single crystals together with the electrochemica l measurements and magnetization measurements confirm that stage n=6 c orresponds to delta=0.055+/-0.05, the high-delta-side of the oxygen-ri ch-oxygen-poor miscibility gap. Furthermore, stage n=4 occurs at a val ue of delta consistent with delta proportional to n(-1). For ceramic s amples it is shown that two different superconducting compounds are fo rmed depending on the oxidation voltage used.