The origin of melt-texture crystal growth process in a simple tube furnace

Abstract

The melt-texture growth (MTG) method has been shown to be effective in fabricating high-Tcsuperconducting bulk samples with highly oriented layers of single crystals. The critical current densityJcof the typical samples are enhanced significantly. Furthermore, making use of the nonzero spatial temperature gradient at certain locations of a common tube furnace, we fabricated Y-123 bulk samples with various dopants allowingJcup to ≈3.0×104 A cm−2 in our recent investigations. We followed up our project by analyzing the relations among the crucial parameters involved in the modified version of the MTG process. These parameters include the temperature gradient, the time rate of change of temperature, the “growth front” of the crystal, etc. Our study indicates that some of the empty space regions that appear between layers are only shallow “gap lines.” True layers of single crystals do exist, and we present an explanation for the growth of crystal layers along special directions as observed.