Structural investigations of the ionic conductivity in zirconia single crystals by neutron diffraction at high temperatures and simultaneously applied electric field

In situ neutron diffraction studies of CaO and Y₂O₃ stabilized zirconia single crystals were performed at elevated temperatures and simultaneously applied DC electric field, i.e. lasting ionic current. Bragg data from Zr_o.85Ca_0.15O_1.85 (CSZ15) were collected at room temperature without electric field, at 1170 K and 1370 K without and with 3.5 V and 1.8 V, respectively, (field vector Eli[Ill]), which generated a current of 60 mA in each case. In case of Zr_0.70Y _0.30O_l.85 (YSZ15) the electric field vector was directed along [001]. At 1170 K three data sets were collected: without field, with 1.5 V (I =60 mA), and with 2.5 V (I = 120 mA). Atomic displacement parameters (a.d.p.'s) were derived in the frame of a non-Gaussian Debye-Waller factor formalism for the oxygens. Corresponding probability density function (p.d.f.) maps and pseudo potential maps were calculated. Most probable curved diffusion pathways run close to < 100 >, independent of the external field direction, applied voltage and the kind of dopant. With lasting ionic current the potential corresponding to p.d.f. > 1% is lowered by about 0.06-0.07 eV.