Diffusion over the temperature range 600-850 degreesC, electrodiffusion at
30 degreesC and effect of the Co substitution on crystalline structure and
electrical characteristics of YBa2Cu3O7-y (YBaCuO) ceramic samples have bee
n investigated by the energy dispersive X-ray fluorescence (EDX), X-ray dif
fraction (XRD), resistivity-temperature and current-voltage measurements. T
he temperature dependence of the cobalt diffusion coefficient (600-850 degr
eesC) via the grain boundaries has been described by the relation D=5.1 x 1
0(-4) exp (-1.12/kT). It is shown that the Co- doping of YBaCuO causes depr
ession of the critical temperature and the critical current density. At the
room temperature Co migrates in d.c. electric field preferentially in the
form of positively charged ions with an effective charge q approximate to 0.6. Electrodiffusion-stimulated orthorhombic- tetragonal transition, decre
ase in critical temperature and critical current density and change of the
form of resistivity-temperature dependence are discovered. (C) 2001 Kluwer
Academic Publishers.