The diffusion of 18O was determined as a function of the Sr content, at temperatures ranging from 300 to 500C, under an O partial pressure of about 1atm. The concentration profiles were measured by using secondary ion mass spectrometry. It was found that the diffusion coefficient decreased (table 85) with increasing Sr contents of between 10 and 20mol% (measurements at lower Sr contents were impaired by porosity). This decrease was due mainly to an increase in the activation energy. This behavior was opposite to that which was expected; that is, an increase in the diffusion coefficient with the increase in vacancy concentration which was caused by adding Sr. It could be explained by assuming that the O vacancies were bound to Sr clusters.
J.L.Routbort, S.J.Rothman, B.K.Flandermeyer, L.J.Nowicki, J.E.Baker: Journal of Materials Research, 1988, 3[1], 116-21
Table 85
Diffusion of O in La2-xSrxCuO4
x | Temperature (C) | D (cm2/s) |
0.10 | 300 | 3.69 x 10-14 |
0.10 | 400 | 8.51 x 10-14 |
0.10 | 500 | 2.69 x 10-12 |
0.15 | 300 | 6.52 x 10-16 |
0.15 | 400 | 3.84 x 10-15 |
0.15 | 500 | 5.59 x 10-14 |
0.20 | 300 | 1.03 x 10-18 |
0.20 | 400 | 9.25 x 10-16 |
0.20 | 500 | 4.09 x 10-15 |