Oxygen Over-stoichiometry Research Articles

Observation of carboxylic groups in the lattice of sintered Ba2YCu3O7-y high-Tc superconductors.

This study reports for the first time the experimental evidence that stable carboxylic groups are present in the lattice of sintered ${\mathrm{Ba}}_{2}\mathrm{Y}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7\ensuremath{-}y}$ superconducting oxides. The carboxylic groups likely originated in the incomplete calcination of the BaC${\mathrm{O}}_{3}$ precursor powder and they could be responsible for the oxygen over-stoichiometry observed in these materials. Further experimental investigations are required concerning in particular the sites of carboxylic groups in the Ba-Y-Cu-O lattice and their effects on the tetragonal-orthorhombic instability.