Thermogravimetric measurements were made, of the deviations in stoichiometry of (Co,Fe,Mn)3-dO4 at 1200C, as a function of the O activity and cationic composition. The observed dependence upon O activity suggested that cation vacancies and cation interstitials were the main defects. Cation tracer (60Co, 59Fe, 54Mn) diffusion data (tables 40 to 42) revealed the existence of minima as a function of the O activity. This showed that cation vacancies and cation interstitials contributed to the cation tracer diffusivity.
F.H.Lu, R.Dieckmann: Solid State Ionics, 1992, 53-56, 290-302
Table 40
Diffusion of 60Co in [CoxFe2(1-x)/3Mn(1-x)/3]3-dO4
as a Function of O Activity at 1200C
O Activity | x | D (cm2/s) |
2.09 x 10-1 | 0 | 5.50 x 10-9 |
2.69 x 10-3 | 0 | 3.24 x 10-10 |
2.30 x 10-6 | 0 | 7.08 x 10-10 |
4.00 x 10-7 | 0 | 2.14 x 10-9 |
2.09 x 10-1 | 0.1 | 8.13 x 10-10 |
4.57 x 10-2 | 0.1 | 2.88 x 10-10 |
7.41 x 10-3 | 0.1 | 9.77 x 10-11 |
4.27 x 10-5 | 0.1 | 3.63 x 10-10 |
1.38 x 10-5 | 0.1 | 6.46 x 10-10 |
1.80 x 10-6 | 0.1 | 2.34 x 10-9 |
8.91 x 10-1 | 0.2 | 2.24 x 10-10 |
2.09 x 10-1 | 0.2 | 1.05 x 10-10 |
1.18 x 10-3 | 0.2 | 2.63 x 10-10 |
1.41 x 10-4 | 0.2 | 1.10 x 10-9 |
8.91 x 10-1 | 0.333 | 1.20 x 10-10 |
2.09 x 10-1 | 0.333 | 2.24 x 10-10 |
3.55 x 10-2 | 0.333 | 6.46 x 10-10 |
1.23 x 10-2 | 0.333 | 1.29 x 10-9 |
Table 41
Diffusion of 59Fe in [CoxFe2(1-x)/3Mn(1-x)/3]3-dO4
as a Function of O Activity at 1200C
O Activity | x | D (cm2/s) |
2.09 x 10-1 | 0 | 6.46 x 10-9 |
2.69 x 10-3 | 0 | 3.47 x 10-10 |
2.30 x 10-6 | 0 | 1.86 x 10-10 |
4.00 x 10-7 | 0 | 5.13 x 10-10 |
2.09 x 10-1 | 0.1 | 8.13 x 10-10 |
4.57 x 10-2 | 0.1 | 2.82 x 10-10 |
7.41 x 10-3 | 0.1 | 8.71 x 10-11 |
4.27 x 10-5 | 0.1 | 6.31 x 10-11 |
1.38 x 10-5 | 0.1 | 1.10 x 10-10 |
1.80 x 10-6 | 0.1 | 3.72 x 10-10 |
8.91 x 10-1 | 0.2 | 1.74 x 10-10 |
2.09 x 10-1 | 0.2 | 6.92 x 10-11 |
1.18 x 10-3 | 0.2 | 3.63 x 10-11 |
1.41 x 10-4 | 0.2 | 1.32 x 10-10 |
8.91 x 10-1 | 0.333 | 2.69 x 10-11 |
2.09 x 10-1 | 0.333 | 3.24 x 10-11 |
3.55 x 10-2 | 0.333 | 7.08 x 10-11 |
1.23 x 10-2 | 0.333 | 1.29 x 10-10 |
Table 42
Diffusion of 54Mn in [CoxFe2(1-x)/3Mn(1-x)/3]3-dO4
as a Function of O Activity at 1200C
O Activity | x | D (cm2/s) |
2.09 x 10-1 | 0 | 8.32 x 10-9 |
2.69 x 10-3 | 0 | 4.90 x 10-10 |
2.30 x 10-6 | 0 | 3.72 x 10-10 |
4.00 x 10-7 | 0 | 1.07 x 10-9 |
2.09 x 10-1 | 0.1 | 1.12 x 10-9 |
4.57 x 10-2 | 0.1 | 3.80 x 10-10 |
7.41 x 10-3 | 0.1 | 1.23 x 10-10 |
4.27 x 10-5 | 0.1 | 1.55 x 10-10 |
1.38 x 10-5 | 0.1 | 2.63 x 10-10 |
1.80 x 10-6 | 0.1 | 9.33 x 10-10 |
8.91 x 10-1 | 0.2 | 2.69 x 10-10 |
2.09 x 10-1 | 0.2 | 1.20 x 10-10 |
1.18 x 10-3 | 0.2 | 1.12 x 10-10 |
1.41 x 10-4 | 0.2 | 3.72 x 10-10 |
8.91 x 10-1 | 0.333 | 5.75 x 10-11 |
2.09 x 10-1 | 0.333 | 7.24 x 10-11 |
3.55 x 10-2 | 0.333 | 1.55 x 10-10 |