Point defects and oxygen diffusion in high T sub c superconductors
Abstract
This paper presents a review of the oxygen tracer diffusion data on the high-temperature oxide superconductors, La(sub 2-x) Sr(sub x) CuO4 and YBa2Cu3O sub 7-delta which have been obtained in our laboratory. The SIMS (Secondary Ion Mass Spectrometry) technique has been used to determine the depth profile of O to 18 from which the diffusion coefficient was calculated. Measurements in the La-Sr-Cu-O system have been performed for x = 0.1, 0.15 and 0.2 and the self-diffusion coefficient was found to decrease with increasing Sr substitution, a fact explained by a defect model in which oxygen vacancies are bound to Sr clusters. Recent measurements in polycrystals of Y-Ba-Cu-O were made in the temperature range of 300 to 600 C at an oxygen partial pressure of 1 atmosphere; they are given by D = 9 x 10 sup -6 exp -(0.89 eV/kT) sq cm/s.
- Publication:
-
Presented at the 7th International Symposium on Ceramics
- Pub Date:
- November 1988
- Bibcode:
- 1988cera.symp...14R
- Keywords:
-
- High Temperature Superconductors;
- Oxygen 18;
- Partial Pressure;
- Point Defects;
- Self Diffusion (Solid State);
- Superconductivity;
- Transition Temperature;
- Barium Compounds;
- Copper Oxides;
- Diffusion Coefficient;
- High Temperature;
- Isotopic Labeling;
- Lanthanum Compounds;
- Mass Spectroscopy;
- Strontium Compounds;
- Yttrium Compounds;
- Solid-State Physics