ausblenden:
Schlagwörter:
-
Zusammenfassung:
Single crystals of YBa2Cu3-xZnxO7-y (x less-than-or-equal-to 0.066) were
obtained through long periodic step growth by adding ZnO to the primary
phase region of the YBa2Cu3O7-y phase on the YBa2Cu3O7-y-BaCu3O4
pseudo-binary line. The solubility of zinc in YBCO is found to be
relatively low. The chemical composition (including oxygen) has been
accurately determined for all the Zn-doped YBCO crystals by EPMA. XRD
showed that all the crystals were orthorhombic and the unit cell volume
increased continuously with increasing zinc concentration. Crystals
which had been annealed in oxygen showed a T(c) at 74, 72, 68 and 63 K
for x = 0.037, 0.042, 0.055 and 0.066, respectively. The primary phase
was found to be located at the region having high fractions of BaCu3O4.
In the course of the crystal growth study, several insulating compounds
with approximate formulae YBaZn3-xCuxOy, Y2(Cu,Zn)xOy and (Y,Cu)BaZn2Oy
were also found from the melt after solidification. The phase of
YBaZn3-xCuxOy was identified to be hexagonal with a approximately 5.0
angstrom and c approximately 9.5 angstrom.
