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The crystalline phases in the superconducting ceramic Bi:Sr:Ca:Cu2:Ox exhibiting either low superconducting transition (≈ 80 K) or both, low and high superconducting transitions (≈ 110 K) are indentified by X-ray and electron diffraction. Two types of modulated structures are observed and their relation to Tc is discussed within the frame of the oxygen-displacive mode theory. Der keramische Werkstoff Bi:Sr:Ca:Cu2:Ox zeigt entweder nur einen einzigen niedrigen supraleitenden Ubergang (≈ 80 K) oder zwei Ubergange, einen niedrigen und einen hohen (≈ 110 K). Die in diesem Werkstoff vorliegenden kristallinen Phasen werden mittels Rontgenbeugung und Elektronenmikroskopie untersucht. Zwei verschieden modulierte Strukturen werden betrachtet und ihr Einflus auf die Ubergangstemperatur im Rahmen der „oxygen-displacive mode”-Theorie diskutiert.

Device quality PbS photoconducting films were obtained by laser plasma vapour deposition on special glass substrates at room temperature and their structure was investigated by X-ray diffraction. High Tc superconducting films of composition Dy 0.2 Y 0.8 Ba 2 Cu 3 O~ 7 and YBa 2 Cu 3 O~ 7 were deposited on sapphire substrate. It was shown for laser deposited YBa 2 Cu 3 O~ 7 that a buffer layer of the same composition predeposited by rf sputtering allows for getting high quality superconducting films.