An evolution of the charge carriers' subsystem in YBa2Cu3Oy single crystals upon annealing in water vapour

摘要

In the present work, we have studied the influence of low-temperature annealing in water vapour on a system of charge carriers by measuring the reflectivity spectra for YBa2Cu3Oy single crystals with low and high oxygen content (y = 6.2 and y = 6.9). It has been shown that lattice parameter c and charge carrier parameters of the YBa2Cu3O6.9 sample remain unchanged upon hydration at 200 degrees C. An intercalation of water in the form of O2- and H+ ions results only in weakening the electron-hole coupling and decrease in the number of excitons. Unlike YBa2Cu3O6.9, the crystal structure of YBa2Cu3O6.2 has more defects, which appear as a result of hydration and an incorporation of OH-groups, which is evidenced by a pronounced change in the parameter c. As a consequence, charge carriers became more localised.