The tracer diffusivity of 18O was determined, at temperatures of between 300 and 850C, by using secondary ion mass spectrometry. It was found that the diffusion of O was markedly anisotropic (table 61). The faster-diffusing component, for migration in the ab-plane, was associated with an activation energy of 0.97eV. There was no break in the Arrhenius plot at the orthorhombic to tetragonal transformation temperature. The diffusion coefficient at 600C was not a sensitive function of O partial pressures ranging from 3kPa to 0.1MPa.

S.J.Rothman, J.L.Routbort, J.E.Baker: Physical Review B, 1989, 40[13], 8852-60

 

 

 

Table 61

Diffusivity of 18O in Cu3Ba2YO7

 

Temperature (C)

PO2 (MPa)

Component

D (cm2/s)

300

0.1

fast

3.96 x 10-13

300

0.1

fast*

1.11 x 10-12

300

0.1

slow

1.62 x 10-14

300

0.1

slow*

1.72 x 10-13

391

0.1

fast*

2.61 x 10-11

391

0.1

slow*

1.52 x 10-12

400

0.1

fast

7.35 x 10-12

400

0.1

slow

2.81 x 10-13

600

0.1

fast

2.80 x 10-10

600

0.1

fast*

1.29 x 10-10

600

0.003

fast

2.23 x 10-10

600

0.02

fast

1.62 x 10-10

652

0.1

fast

8.00 x 10-10

711

0.1

fast

1.38 x 10-9

780

0.1

fast

2.49 x 10-9

850

0.1

fast

6.33 x 10-9

*material with up to 4at% of excess Cu