Mullite: O Diffusion

The tracer diffusion of 18O in Czochralski-grown mullite single crystals, along [010] and [001], was investigated. The diffusion coefficients ranged from about 5 x 10-20m2/s (1250C) to about 9 x 10-18m2/s (1525C). The data did not reveal any significant anisotropy. The values of the activation enthalpy (4.5eV) and of the activation entropy (3.4k) suggested that atomic transport occurred via thermally activated vacancies.

Secondary Ion Mass Spectroscopy Study of Oxygen-18 Tracer Diffusion in 2/1-Mullite Single Crystals. P.Fielitz, G.Borchardt, M.Schmücker, H.Schneider, M.Wiedenbeck, D.Rhede, S.Weber, S.Scherrer: Journal of the American Ceramic Society, 2001, 84[12], 2845-8

Table 67

Diffusion of Co in NiO

Temperature (C)	PO2 (atm)	D (cm2/s)
1100	0.21	1.94 x 10-11
1100	0.0005	1.39 x 10-11
1125	0.00019	1.6 x 10-11
1170	0.21	5.4 x 10-11
1180	0.00014	2.3 x 10-11
1200	0.21	7.94 x 10-11
1245	0.011	9.8 x 10-11
1245	0.0025	6.4 x 10-11
1245	0.00058	5.36 x 10-11
1245	0.00018	4.8 x 10-11
1245	0.00003	3.6 x 10-11
1245	0.000001	2.56 x 10-11
1245	0.0000002	2.28 x 10-11
1300	0.21	3 x 10-10
1315	0.00008	9.31 x 10-11
1394	0.0005	3.3 x 10-10
1400	0.21	8.13 x 10-10
1500	0.21	2.26 x 10-9
1510	0.0006	1.17 x 10-9
1600	0.21	5.46 x 10-9
1700	0.21	1.29 x 10-8

Table 68

Diffusion of Mg in NiO

Temperature (C)	PO2 (atm)	D (cm2/s)
1016	0.00003	8.6 x 10-13
1100	0.21	3.8 x 10-12
1103	0.00001	1.35 x 10-12
1165	0.00006	3.05 x 10-12
1200	0.21	1.75 x 10-11
1210	0.00005	5.36 x 10-12
1210	0.011	1.82 x 10-11
1210	0.0025	1.5 x 10-11
1210	0.00058	1.1 x 10-11
1245	0.00018	1.0 x 10-11
1245	0.00005	7.54 x 10-12
1245	0.00003	6.86 x 10-12
1245	0.000002	6.76 x 10-12
1296	0.00007	1.85 x 10-11
1300	0.21	6.1 x 10-11
1305	0.00005	2.07 x 10-11
1400	0.21	1.6 x 10-10
1400	0.00016	5.53 x 10-11
1485	0.00015	1.29 x 10-10
1500	0.21	3.8 x 10-10
1600	0.21	1.1 x 10-9
1700	0.21	2.5 x 10-9