The tracer diffusion of O was measured mainly in the c-axis direction of monocrystalline samples, at temperatures of between 300 and 650C, by using secondary ion mass spectrometry. Other measurements were made of diffusion on the ab-plane of twinned crystals and in the b-axis direction of non-twinned crystals. It was found that the diffusivity in the c-axis direction was about 106 times lower than the diffusivity in polycrystals at 400C. The diffusivity in the b-axis direction was at least 100 times faster than that in the a-axis direction at 300C. Within an experimental uncertainty of a factor of 2, the O diffusivity in polycrystals was independent of the O partial pressure at 400C.

Anisotropy of Oxygen Tracer Diffusion in Single-Crystal YBa2Cu3O7-δ.  S.J.Rothman, J.L.Routbort, U.Welp, J.E.Baker: Physical Review B, 1991, 44[5], 2326-33

 

Table 62

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