Large Bi-2212 single crystal growth by the floating-zone technique

Effects of growth velocity on the crystal-growth behavior of Bi 2Sr 2Ca 1Cu 2O x (Bi-2212) have been studied by the floating-zone technique. The results show that a necessary condition for obtaining large single crystals along the c-axis is that the solid–liquid interface of a growing rod maintains a stable planar growth front. The planar liquid–solid growth interface tends to break down into a cellular interface when the growth velocity is higher than 0.25 mm/h. Single crystals of up to 50×7.2×7 mm 3 along the a-, b- and c-axes, respectively, have been cut from a 7.2 mm diameter rod obtained with optimum growth conditions. T c onset is 91 K as determined from magnetization measurements on as-grown crystals. Optical polarization microscopy and neutron diffraction show that the quality of the large single crystals is good.