Printed book · Report
Defektstrukturer i keramiske superledere
The influence of the defect structure on the superconducting properties of high temperature superconductors has been studied experimentally and by computer simulation technique. The relation between defect structure and the superconducting transition temperature, T_c, has been studied in Co-doped YBCO (YBa_2Cu_3_-_yCo_yO_6_+_x, 0 #<=# y #<=# 0.5), and it has been shown that the model, which has been established to account for the influence of oxygen ordering on T_c in oxygen deficient YBCO (YBa_2Cu_3O_6_+_x, x < 1), is valid also for Co-doped YBCO.
A three-dimensional model for the oxygen ordering in undoped YBCO has been introduced and used to analyse experimental structural data. Good agreement between the model predictions and the experimental data has been established. Experimental studies of crystal structure, oxygen stoichiometry, and electrical and magnetic properties of Nd_1_._8_5Ce_0_._1_5CuO_4_+_x have been carried out in order to elucidate why this material apparently is an electron conductor in the superconducting phase, and not as the other high temperature superconductors, a hole conductor.
Structural studies on Pb_2Sr_2Y_1_-_xCa_xCu_3O_8 (0 #<=# x #<=# 0.5) have been carried out by neutron powder diffraction and it has been shown how the Ca-stoichiometry influence the Cu-valence in the superconducting CuO_2-planes. The structural ordering of epitaxial thin films of YBCO and Bi_2Sr_2CaCu_2O_8_+_x deposit on heated substrates of SrTiO_3, MgO, LaAlO_3 and NdGaO_3 has been studied by x-ray diffraction and Rutherford Backscattering spectroscopy, and the structural ordering has been analysed in relation to the superconducting properties. (au) (9 ills., 10 refs.).
Language: | Danish |
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Publisher: | Risø National Laboratory |
Year: | 1993 |
Pages: | 20 s. |
Series: | Denmark. Forskningscenter Risoe. Risoe-r |
ISBN: | 8755019315 and 9788755019317 |
ISSN: | 01062840 |
Types: | Printed book and Report |