GROWTH OF LARGE SINGLE-CRYSTALS USING THE IMPROVED LAMP-IMAGE FLOATING-ZONE FURNACE - APPLICATION TO LA2-XSRXCUO4

We grew large single crystals of La2-xSrxCuO4 reproducibly over a wide doping range using an improved travelling solvent floating zone (TSFZ ) method. We performed a simulation on the lamp-image focusing to find an optimum condition for a steep temperature gradient along the rod. Based on the results of simulation, we adapted smaller lamps and shiel ded the partial area of the mirror surfaces, The improvement of the fo cusing had a great effect on keeping the molten zone stable for more t han 100 h, Stabilization of the molten zone improves both the reproduc ibility of the crystal growth and the quality of the grown crystals.