Optimization of Single Crystal Preparation of Bi 2 Sr 2 CaCu 2 O x Superconductor by the Travelling Solvent Floating Zone Method

Optimization of single crystal preparation of the Bi 2.2 (Sr, Ca) 2.8 Cu 2.0 O y superconductor by the travelling solvent floating zone method has been performed with the intention of obtaining large single crystals and improving the superconductive transition temperature, T c . The composition ratio, Sr/Ca, and the oxygen partial pressure of growth atmosphere, P O 2 , were varied in the crystal growth. A single crystal typically obtained was a thin plate of the dimensions of 5×50×2 mm 3 . The thickness of the crystal was the largest in the crystal growth at Sr/Ca=1.4, while no distinct change was observed in the resulting crystals in the range of 22∼100 kPa. Electric and magnetic properties, the formal charge of copper ions and existence of ion defects are discussed.