OXYGEN DIFFUSION IN SILVER-FREE AND SILVER-DOPED YBA2CU3O7-DELTA SINGLE-CRYSTALS

Oxygen diffusion in undoped and silver-doped YBa2Cu3O7-delta (YBCO) si ngle crystals has been investigated by isothermal resistivity measurem ents in the temperature interval 550-750 degrees C. The diffusion coef ficients for silver-doped crystals were found to be an order of magnit ude lower compared with undoped ones. Further, the activation energy f or oxygen diffusion was found to be considerably higher for Ag-doped c rystals. Analysis of data on the equilibrium value of resistivity as a function of temperature and magnetization measurements made on sample s quenched from an annealing temperature of 850 degrees C, indicates t hat silver doping stabilizes the YBCO phase with higher oxygen content .