Synthesis of Single Crystals of a High-Temperature Super-conductor YBa_2Cu_3O_(7-delta) From a Fluorine-Contained Solution-Melt

摘要

The laboratory technological technique of fabrication of HTSC single crystals YBa_2Cu_3O_(7-delta) (T_c approx=90K, DELTA T_c approx=1.0K) with size up to 0.25sm~2 from nonstoichiometric fluorine-contained solution-melt (YO_(1.5))(BaO)_(4-x)(BaF_2)_x(CuO)_(10)(2>=x>=0) is developed by means of the method of combination of mass formation of the centres of growth and Czochralsk's oriented crystallization. By TAD data, the temperature of crystallization of eutectic mixture can be decreased by application of BaF_2. Moreover, the addition of BaF_2 gives a possibility to increase the growth rate of crystals. The optimum content of BaF_2 in start composition (x=0.2) is determined. The surface morphology is examined by the method of atomic force nanoscopy. There are significant differences in the surface morphology between YBa_2Cu_3O_(7-delta) single crystals grown from melts with BaF_2 and without BaF_2.