The diffusion of 139Ce in polycrystalline NiO was studied at 600 to 1100C, under O at a pressure of 1atm. The solubility of Ce in the NiO bulk was negligible, but Ce was soluble at NiO grain boundaries and dislocations. Consequently, the Ce tracer diffused only along

Table 151

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