Enhanced stability of floating-zone by modifying its liquid wetting ability and fluidity for YBa2Cu3O7-δ crystal growth

As an ideal material platform for deep investigations on superconductivity, high purity YBa2Cu3O7-δ (Y123) single crystals have been highly concerned and requested recently. However, it is very difficult to grow such crystals by the conventional travelling-solvent floating-zone (TSFZ) process due to the intrinsic instability of floating zone caused by the liquid loss. To overcome this obstacle, the feed rod with modified precursor powder (MPP) of 0.5Y2O3+ Ba2Cu3O5 was adopted, instead of the conventional one (Y123). Our experimental results proved that less Ba3Cu7Oy solvent penetrated to the MPP-rod due to its low wettability. Furthermore, it was also observed that less melt dropped down from the floating zone owning to its low fluidity, caused by low dimension of bubbles and Y211 particles generated from the MPP-rod. Consequently, the molten zone was remarkably stabilized and the Y123 single crystal was successful grown. The effective size of the grown boule was about 5 mm (Ø) × 30 mm. This new conception of altering precursor components for continuous TSFZ growth is universally worth of producing other functional materials.