一方向凝固した超伝導YBCO酸化物と銀の接合体作製と界面特性

概要

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Two joining methods were investigated to develop the low resistivity joint of silver and Y-Ba-Cu-O superconducting oxide (YBCO) with the columnar crystal structure of 123 phase (YBa_2Cu_3O_<7-x>), which was obtained by unidirectional solidification from liquid+211 (Y_2BaCuO_5) phases. One method was a solid state processing by the use of hot-press, in which no detectable interaction layer was formed. The interface resistivity (ρ_c) at 77 K measured by the four-prove method decreased with the increase in joining temperature (T) or joining pressure (P), and the minimum value : ρ_c= 2×10^<-12>Ω・m^2 was obtained when the joining conditions were P=32 MPa, T=873 K, t=3600 s. The other method was a liquid state processing by using molten silver, in which remarkable interaction layer was formed. Since the reaction was caused by the decomposition of 123 phase to liquid+211,the interaction layer was recovered to 123 phase by slow cooling and solidification. This recovering treatment remarkably decreased ρ_c, and the minimum ρ_c value was as low as about 10^<-12>Ω・m^2 at 77 K, which satisfied the stability criteria for composite conductors.
社団法人溶接学会の論文
1996-02-05