Large Single Crystal growth of Bi-2212 superconducting oxide

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 behaviour of Bi-2212 superconducting materials. It shows that a necessary condition for large single crystal growth 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 0.3 mm/h, or while deviating from the optimum starting composition of the feed rod Bi$_{2.1}$Sr$_{1.9}$Ca$_{1.0}$Cu$_{2.0}$O$_{x}$. The single crystals up to 100$_{\ast }$7$_{\ast }$3.8 mm$^{3 }$along the $a$-, the $b$- and the $c$-axis have been grown in a \textit{$\Phi $}7mm rod with optimum growth conditions. The single crystals of up to 50*7*3.8 mm$^{3}$ have been picked up from the cut section of the as-grown rod. The neutron measurements show that the quality of the single crystals is good. The superconducting transition temperature $Tc_{onset}$ by SQUID is 91K for as-grown crystals.