RELATIONSHIP BETWEEN MICROSTRUCTURE AND OPTICAL-PROPERTIES IN HIGH T(C)-SUPERCONDUCTORS

Spectroscopic ellipsometry investigations on several groups of high T( c) superconductors have been performed in the region of 1-5 eV. The op tical data have been compared with results of structural studies made by transmission electron microscopy and X-ray diffraction. The depende nce of the optical features in the dielectric function on the microstr ucture of single crystals has been determined. The microstructure in a Cu(1)-O layer has been shown to be closely related to the optical fea tures in the region of 4 eV for (123)-type compounds. The characterist ic features in the dielectric function spectra have been determined fo r single crystals of isostructural (2212)-type phases. In Pb-based (12 12)-type single crystals a strong optical anisotropy in the a-b plane has been predicted to be related to an ordering of oxygen vacancies in the Pb-O plane.