CHIN Ken Tohoku University, Assistant Professor, 電気通信研究所, 助教授 (90241588)
YAMASHITA Tsutomu Tohoku University, Professor, 未来科学技術共同研究センター, 教授 (30006259)
ITO Hidenobu Faculty of Engineering, Assistant Professor, 工学部, 助教授 (90113703)
Recent attention has been on single crystal whiskers of high T_ο superconductors because of their useful characteristics such as perfect crystallinity, absence of dislocations, peculiar dimensions with extremely small cross sections, and excellent superconducting properties. Developments suggest that the high-T_ο whiskers are useful in the fabrication of electronic devices with high frequency THz band using intrinsic Josephson effects and related phenomena, such as Josephson plasma oscillations.
Bi_2Sr_2CaCu_2O_χ (Bi-2212), (BiPb)_2Sr_2Ca_2Cu_3O_<10+δ> ((BiPb)-2223) and R_1Ba_2Cu_3O_χ (R-123)(R=Y, La, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, and Lu) single-crystal whiskers were grown from annealing sintered Te and Ca doped precursor pellets. The optimal precursor composition is Ca-rich Bi_2Sr_2Ca_2Cu_2Te_<0. 5>O_χ for Bi-2212, mixture of single-phase (BiPb)-2223 with 0.5TeO_2 for Bi-2223, and R_1Ba_2Cu_3Te_<0.5>Ca_<1.0>O_χ for R-123. The whiskers have excellent crystallinity with contain no Te element, and exhibit interesting intrinsic Josephson effects along the c axis.