Chemical evidence for peroxide in YBa₂CU₃O₇

Dissolution studies on both normal 16O and 18O enriched YBa2Cu3O7 in normal and 18O enriched acid solutions were used to show that the origin of the evolved oxygen, which was determined by GC mass spectrometry, is from the solid and not the solvent. This implies strong oxygen-oxygen interactions indicative of peroxide formation, as predicted by de Groot et al(1), and is additional evidence that the oxygens are the hole carriers in these Cu-oxide superconductors. © 1988 Elsevier Science Publishers B.V.