A mosaic of three twinned single crystals of
were utilized in this
experiment. The
crystals were of extremely high quality, as
characterized by low-field magnetization, ab-plane resistivity, microwave
surface resistance and heat capacity measurements [85]. For example,
the superconducting transition temperature Tc, determined by
magnetization measurements was found to be 93.2K with a relatively
narrow transition width
K.
The
single crystals were grown by a flux method in yttria-stabilized
zirconia crucibles. CuO-BaO flux was poured over hot (950-
C)
crystals initially grown from high purity Y2O3 (
),
CuO (
)
and BaCO3 (
)
compounds. To ensure
each crystal had the identical oxygen concentration corresponding to the
maximum Tc, all three crystals were carefully annealed prior to the
experiment. For 3 days the crystals were held in 1 atmosphere of
O2 at
C, followed by 14 days at
C before
rapidly cooling to room temperature. Together the three crystals had a
total mass of 53mg.