Growth and characterization of BiSCCO 2212 whiskers from melts containing various La contents

Bi2Sr2-xLaxCaCu2O8+d superconducting whiskers were successfully grown from Bi-rich meltscontaining various La contents. Effect of La-doping on the whisker growth, structure and superconductivity has been studied. It has been found that the whiskers can be grown only from La-doped melts, no whisker was obtained from the La-free melt x=0. Within the doping region x=0.025-0.3, all the grown whiskers are of the Bi-2212 pure phase. The c-axis lattice constant decreases with increasing the La content in the melt. The effect of La doping on the superconductivity is similar to that of other rare earth dopings in this system, it depresses and broadens the transition. The melt method used in this letter is compared with the other two kinds of processes used so far, usual powder sintering and glassy precursor annealing method. The possible growth mechanism of the whiskers from the melt method is discussed briefly.