Redistribution of oxygen ions in YBa2Cu3O7–x single crystals due to external hydrostatic pressure
Yu.I. Boiko, V.V. Bogdanov, R.V. Vovk, G.Ya. Khadzhai, and S.V. Savich
V.N. Karazin Kharkiv National University, 4 Svoboda Sq., Kharkiv 61022, Ukraine
Received June 8, 2017, revised Jule 31, 2017
The effect of high hydrostatic pressure on the temperature dependences of the electrical resistivity in the basal plane of YBa2Cu3O7–x single crystals with oxygen deficiency is studied. It is established that the external hydrostatic pressure Р ≈ 7 kbar substantially intensifies the process of diffusion coalescence of oxygen clusters, that is, it causes the growth of their average size. This, in turn, leads to an increase in the number of negative U-centers, the presence of which leads to the appearance of a phase capable of generating paired carriers of electric charge and, accordingly, characterized by a higher transition temperature Тс. Within the framework of the same hypothesis on the mechanism of diffusion coalescence of oxygen clusters, a change in the form of the temperature and time dependences of the electrical resistivity under the action of external hydrostatic pressure is discussed.
PACS: 74.72.–h Cuprate superconductors.
Key words: single crystals YBa2Cu3O7–x, hydrostatic pressure, coalescence, oxygen deficiency, single-file diffusion.
Published online: November 28, 2017