DETERMINATION OF OXYGEN DIFFUSIVITY IN TETRAGONAL YBA2CU3OX USING A SOLID-STATE ELECTROCHEMICAL METHOD

A solid state electrochemical technique is used to determine the oxyge n chemical and component diffusion coefficients in the tetragonal phas e of YBa2Cu3Ox. The measurements are performed at 850 degrees C, as a function of oxygen partial pressure and oxygen nonstoichiometry. The s ample is held in a calcia-stabilized zirconia titration cell. An oxyge n ionic current pulse is applied to the cell, and the EMF signal is mo nitored as a function of time. The diffusion coefficients are evaluate d by analyzing the time dependence of the EMF, during and after the cu rrent pulse. It is found that the oxygen chemical diffusion coefficien t increases weakly with x, with an average value of (D) over tilde sim ilar to 5 . 10(-5) cm(2)/s at T = 850 degrees C. The oxygen component diffusion coefficient is found to be independent of nonstoichiometry, with a value of D-o similar to 5 . 10(-5) cm(2)/s.