Variation in the Kind of Formed Superconducting Oxide and Microstructure with Heat-Treatment Temperature in Yb-Ba-Cu-Ag Ribbons

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J. Korean Ceram. Soc. > Volume 35(1); 1998 > Article

Journal of the Korean Ceramic Society 1998;35(1): 79.

Yb-Ba-Cu-Ag 리본의 열처리 온도에 따라 형성된 초전도 산화물의 종류와 미세구조의 변화

송명엽

전북대학교 신소재공학부

Variation in the Kind of Formed Superconducting Oxide and Microstructure with Heat-Treatment Temperature in Yb-Ba-Cu-Ag Ribbons

ABSTRACT

Melt spun YbBa2Cu3Agx(x=0, 5, 12, 16 and 53) precursor alloy ribbons were oxidized at 263-330$^{circ}C$ and treated at 820$^{circ}C$, 855$^{circ}C$ and 885$^{circ}C$ under 1.0 atm oxygen pressure. In the ribbons treated at 820$^{circ}C$, 855$^{circ}C$and 885$^{circ}C$ 1-2-4 phase (YbBa2Cu4O8) and 1-2-3 phase (YbBa2Cu3O{{{{ OMICRON _7-$delta$ }})were formed respectively. The shape of 1-2-4 phase was distorted or ellipsoid. The 2-4-7 and 1-2-3 phases tooked the shape of bar. All the ribbons showed zero critical current density Jc at 77K in zero magnetic field. By considering the shape and the highest critical temperature (among the three phases) of the 1-2-3 phase we tried to increase the critical current density of the ribbons treated at 885$^{circ}C$ by press deformation. About tenribbons were stacked and coupled by press deformation and then treated at 885$^{circ}C$ These 1-2-3 phase did not show any texture in any of the ribbons. However they exhibited weak texture in the multilayered specimens. Among the multilayered specimens YbBa2Cu3Ag16 exhibited a Jc of 180 A/cm2 Among the above ribbons YbBa2Cu3Ag16 ribbon has the optimum composition to produce textured superconducting oxide with improved Jc by press deformation. Onset critical temperatures Ton of the multilayered YbBa2Cu3Agx(x=5, 12, 16 and 53) were measured as 88-90 K.

Key words: Melt spinning, Yb-Ba-Cu-Ag ribbgons, Heat-treatment temperature, Superconducting Oxides, Micro-structure, Multilayered specimens.