Single-crystal growth of Bi₂Sr₂Ca₂Cu₃O_10+δ (Bi-2223) by TSFZ method

The traveling solvent floating-zone (TSFZ) method has the potential advantage over the usual flux method that crystal growth can be performed at one point on the temperature-composition phase diagram, and provides an opportunity to grow large single crystals even if their crystallization field is very narrow. Here, we report the first successful preparation of the triple-layered system Bi₂Sr₂Ca₂Cu₃O_10+δ (Bi-2223) single crystals by improving the TSFZ method condition by applying slow growth velocity and higher temperature gradient. The obtained crystals are as large as 4×2×0.1 mm³. X-ray diffraction pattern shows only sharp Bi-2223 peaks, confirming its good crystallinity. DC susceptibility of the as-grown samples exhibits a sharp superconducting transition with T_c = 105 K. After annealing the sample under O₂ flow at 600 °C, T_c increased to the maximum value (= 110 K). High-resolution transmission electron microscope images were taken to investigate the phase purity. It confirms that the crystals cleaved from the last part of grown boule are almost single-phase Bi-2223.