A comparison of the effects of PtO<sub>2</sub> and BaSnO<sub>3</sub> additions on the refinement of Y<sub>2</sub>BaCuO<sub>5</sub> and magnetization of textured YBa<sub>2</sub>Cu<sub>3</sub>O<sub>6+x</sub>
C Varanasi; M A Black; P J McGinn; C Varanasi; Dept. of Electr. Eng., Notre Dame Univ., IN, USA; M A Black; Dept. of Electr. Eng., Notre Dame Univ., IN, USA; P J McGinn; Dept. of Electr. Eng., Notre Dame Univ., IN, USA
Журнал:
Superconductor Science and Technology
Дата:
1994-01-01
Аннотация:
Y<sub>2</sub>BaCuO<sub>5</sub> (211) and liquid (L=3 BaCuO<sub>2</sub>:2CuO) were used as the precursor materials to study the effect of additions of BaSnO<sub>3</sub> and PtO<sub>2</sub> on the coarsening behaviour of 211 particles in the liquid above the peritectic temperature of YBa<sub>2</sub>Cu<sub>3</sub>O<sub>6+x</sub> (123), and the magnetic properties after melt texturing. Additions of BaSnO<sub>3</sub> and PtO<sub>2</sub> both reduced the coarsening of 211, but PtO<sub>2</sub> did so much more effectively. The PtO<sub>2</sub> additions were found to refine 211 by altering the 211/liquid interfacial energy and/or Y diffusivity, and not by acting as heterogeneous nucleation sites. BaSnO<sub>3</sub> additions were found to not be inert in the melt. They reduce 211 coarsening by acting as a Y sink. Magnetization measurements at 20, 40 and 60 K on crushed melt-textured 123 samples showed enhanced intragrain flux pinning effects in samples prepared from 211+L+PtO<sub>2</sub> as compared with 211+L+BaSnO<sub>3</sub> or 211+L precursor samples.
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