CHARACTERIZATION OF YBA2CU3O7-DELTA SINGLE-CRYSTALS GROWN FROM CHARGES CONTAINING SILVER-NITRATE

Single-crystal growth of YBa2Cu3O7-delta has been studied using starti ng charges containing known amounts of Ag in the form of AgNO3. The as -grown crystals are found to undergo a sharp transition to the superco nducting state at 90 K, showing that the addition of AgNO3 facilitates their oxygenation. The measured room-temperature resistivities, both in plane (rho(ab)) and out of plane (rho(c)), for the grown crystals a re found to be the lowest among the values reported so far. The anisot ropy in resistivity (rho(c)/rho(ab)) at 300 K is found to be roughly o ne-half of the value measured for the crystals grown from charges free from AgNO3. The angular dependence of transport critical current for the doped crystals has been measured at 82 K and for an applied magnet ic field of 0.9 T. The results have been analysed using the existing t heoretical models.