Vapour-liquid-solid (VLS) growth mechanism of superconducting Bi-Sr-Ca-Cu-O whiskers

Growth of superconducting Bi-2212 whiskers by the vapour-liquid-solid OILS) mechanism is reported for the first time. Formation of a Bi-rich liquid phase at the nucleation site is believed to cause the growth by the VLS mechanism. The growth proceeds by the precipitation of atomic species at the solid-liquid interface as long as the liquid phase is in the superstaturated state. Whiskers grown by this mechanism are free from the inter-growth of either low T-c (2 2 0 1) or high T-c (2 2 2 3) phases. The grown whiskers possess compositional inhomogeneity due to the decrease in degree of supersaturation of the liquid phase as the growth progresses. Continuous supply of constituent atomic species at the growth site facilitates the growth of large whiskers of uniform composition. The resistivity measurements reveal a superconducting transition at 78 K. (C) 2001 Elsevier Science B.V. All rights reserved.