SUPERCONDUCTING AND STRUCTURAL-PROPERTIES OF HOMOGENEOUS BISRCACUO-(2212) SINGLE-CRYSTALS PREPARED BY SOLUTION GROWTH

The modified method for growing of single crystal BSCCO (2212) from solution-melt in KCl was developed. The dependency of crystal properties on growth conditions was studied The crystals have platelet-like form with thickness of about 200 mum and lateral sizes up to 3 mm. Chemical composition corresponds to formula Bi2.4Sr1.5Ca0.9 Cu2.2O8+delta. X-rav diffraction showed the block structure of the crystals with block sizes 100 200 mum and its misorientation 1-degrees-2-degrees. Crystals have lattice parameters a = b = 5.39 angstrom. c = 30.731 angstrom. The T(c) and DELTAT(c) measured by d.c. resistive and a.c. susceptibility techniques were T(c) = 80 +/- 3 K and DELTAT(c) (10%-90%) = 2-6 K. The measuring of energy gap parameter by break-junction tunneling technique results in value 2DELTA(0)/k(B)T(c) congruent-to 7. The dynamic conductance of tunneling junction showed the additional structures due to peaks in the BSCCO phonon density of states. The analysis of the results allows us to conclude that the presence of atmospheric oxygen during crystal lattice forming has more effect than post-annealing in oxygen of as-grown crystals.