PUB - Publikationen an der Universität Bielefeld

We report on the growth procedure of Bi2Sr2CaCu2O8+delta and Bi2Sr2CuO6+gamma single crystals. The T(c) of Bi2Sr2CaCu2O8+delta crystals. determined by bulk and surface resistance and susceptibility measurements, varies between 78 K and 92 K depending on the oxygen concentration. The surface resistance drops by one order of magnitude when entering the superconducting state. The microwave losses at 3 GHz of the Bi2Sr2CaCu2O8+delta crystals are much higher than those of comparable YBa2Cu3O7-x crystals. The surface quality of the Bi2Sr2CaCu2O+delta and Bi2Sr2CuO6+gamma single crystals is investigated on different length scales using optical microscopy (1-5000 mum), scanning electron microscopy (0.1-500 mum) and scanning tunneling microscopy (STM) (1-1500 angstrom). STM images with atomic resolution are obtained for both Bi2Sr2CuO6+gamma and Bi2Sr2CaCu2O8+delta single crystals. Their structural bulk quality is tested by several X-ray diffraction techniques, detecting no impurity phases in the crystals. The vertical and lateral homogeneity of the chemical composition of the single crystals is revealed by means of sputtered neutrals mass spectrometry and energy-dispersive X-ray fluorescence, respectively.