Ceramic and Glass Materials

188 O.A. Graeve

P

sRT

=

⎛

⎝⎜

⎞

⎠⎟

=× −

⎧ ±

⎨

700 2 34 10− 45300 1200

2

Torr:D cm .exp^2 cal/mol

⎩⎩

⎫

⎬

⎭

. (6)

According to Ikuma et al. [59], surface diffusion and lattice diffusion should be sepa-
rated and result in the following diffusion coefficients:

Dsurface /s

RT

cm

2 kJ/mol

()=× −

⎧

⎨

⎩

⎫

⎬

⎭

584 10. exp−^12 75 3. (7)

Fig. 17Oxygen diffusion in monoclinic zirconia spheres at 300 Torr [57] (reprinted with

permission)

Fig. 18Oxygen diffusion in monoclinic zirconia spheres at 700 Torr [58] (reprinted with

permission)