A solid-state electrochemical cell with yttria-stabilized ZrO2 was used to determine the O ion conductivity, and thereby the O ion diffusivity, by means of impedance measurements at temperatures ranging from 500 to 850C. The activation energies for O diffusion were between 1.2 and 1.25eV at temperatures ranging from 500 to 750C, and between 2.52 and 2.69eV at temperatures ranging from 800 to 850C. It was found that O diffused faster in sintered samples (table 84) than in hot-pressed ones (table 85). The c-direction texturing of the latter, and the resultant slow diffusion in that direction, were suggested to be responsible. In the low temperature range, O ion diffusion in the grain boundaries controlled diffusion whereas, at high temperatures, diffusion in the grains was the controlling process.

W.Zhu, P.S.Nicholson: Journal of the Electrochemical Society, 1995, 142[2], 513-8

Table 85

Diffusivity of O Ions in Hot-Pressed Cu3Ca2Bi2Sr2PbOx