  Single-crystal whiskers of RBa2Cu3Ox (R-123, R = Sm, Eu, Gd, Dy, Ho, Er, Tm,
Yb, and Y) were successfully grown from Sb- or Te-doped precursors with a
nominal composition of R1.5Ba2.75-3.00Cu3M0.5Ox (M: Sb,Te). The whiskers were
grown parallel to the ab-plane with the following typical dimensions: 2-8 mm in
length, 20-80 \mum in width, and 10-30 \mum in thickness. In the case of
rare-earth ions (R3+) with a small ionic radius (Dy, Ho, Er, Tm, Yb, and Y),
R-123 whiskers were grown from Te-doped precursors. The growths of Y-123 and
Ho-123 whiskers were confirmed using both Te-doped and Sb-doped precursors. On
the other hand, for rare-earth ions (R3+) with a large ionic radius (Sm, Eu,
and Gd), R-123 whiskers were grown only from Sb-doped precursors. Sb and Te
were not detected in the grown whiskers by electron probe microanalysis. The
anisotropies of R-123 single-crystal whiskers in the flux liquid state were
estimated to be 6.0-33 from the angular dependence of their resistivities under
various magnetic fields. The anisotropy increased with decreasing
superconducting transition temperature.
