Making large, single crystal, 123 YBCO superconductors

We make large (in excess of 2 cm in diameter), Single crystal
YBa-Cu-Oz-123 YBCO crystals, where Xs O.6, in a sev
enteen Step proceSS or Some variant thereof from finely
ground and well mixed 123 YBCO and 211 YBCO powders
with a Small amount of Pt by controlling the rate of cooling
from within a compact of the powders using a temperature
gradient in the radial and axial planes (independently) of
about 1-1 C./inch diameter of compact to nucleate the
crystal growth. We promote crystal growth as well using a
Samarium oxide seed crystal, preferably SmBa-Cu-Ozo
where ys 1.6. After nucleation we cool the compact slowly
at a rate from about 0.1-1 C./hr to promote the single
crystal development.