SPIRAL GROWTH OF BI2SR2CACU2OY SINGLE-CRYSTALS USING KCL FLUX TECHNIQUE

Crystals of Bi2Sr2CaCu2Oy (Bi2212) have been grown using KCI as flux. It was found, for the first time, the Bi2212 single-crystal growth was mainly controlled by a spiral growth mechanism if the crystals were g rown on the flux surface. Single, double and three-head spirals with s quare and polygonized shapes were observed. Magnetisation measurements show an enhanced flux pinning in the spiral grown crystals compared w ith crystals grown through a layer-by-layer mechanism. The enhancement in flux pinning may be attributable to the spiral edges and the screw dislocations induced by the spiral growth of the crystals.