Crystal Growth of High-T_c Superconductor Bi₂Sr₂Ca₁Cu₂0_x by Floating Zone Method

Abstract

A floating zone method was used to study the effects of the growth velocity and starting composition of the feed rod on the crystal growth behavior of Bi2212 oxides. It shows that a necessary condition for large single crystal growth along the c-axis is that the solid-liquid interface of a rod maintains a planar interface during crystal growth. The planar solid-liquid interface tends to break down into the cellular interface while increasing the velocity from 0.2 mm/h or while deviating from the optimum starting composition. The single crytals up to 20*5.5*1.5 mm³ along the a-, the b- and the c-axis have been grown in the Φ 6.4mm rod with optimum growth conditions. The single crystals of up to 5*5.5*1.2 m m ³ have been picked up from the cut section of the as-grown rod. X-ray Laue measurements show that the quality of the single crystals is good. The superconducting transition temperature Tc _onset by SQUID is 91 K for as-grown crystals.