Effect of Temperature on La1.85Sr0.15CuO4 Single Crystal Growth by Floating Zone Method

Abstract

Superconducting single crystals of La1.85Sr0.15CuO4 have been grown at various temperatures without single crystal seeds by the traveling-solvent floating-zone method. In order to avoid the formation of bubbles during the crystal growth process, a flowing atmosphere of 2 atm oxygen or 1 atm air was applied in different temperature range. It was found that the crystal quality could be improved by raising the growth temperature in a certain range, and the orientation changed from (110) to (100) at higher temperature. X-ray diffraction results showed that the full-width at half-maximum of the best as-prepared crystal was 0.086°. The crystals grown in 2 atm oxygen showed a superconducting transition temperature (Tc) of 37.3 K, while the crystals grown in floating air showed a Tc of about 35 K and it could be improved to 36.5 K by annealing in flowing oxygen.