CALCIUM DOPING INTO YBA2CU3OY CERAMICS BY THE SOED METHOD

Calcium doping into YBa2Cu3Oy (YBCO) ceramics by the SOED (solid oxide electrochemical doping) method was examined in detail. The electrolys is system consists of(+)Ag/Ca-beta ''-Al2O3/YBCO/Ag-beta '' Al2O3/Ag(- ) where the Ba2+ ion in YBCO is substituted by a Ca2+ ion under electr ical force (electro-substitution). Ca2+ is mainly doped into the grain boundaries at low current density but is doped into the grain bulk as well as the grain boundaries at high current density. The amount of t he doped Ca2+ ion saturated with an increase in electrolysis time, bec ause the Ca2+ ion moves through the YBCO sample into the Ag-beta ''-Al 2O3 during the electrolysis. The unit cell volume of the YBCO whose gr ain bulk was doped with Ca2+ was much smaller than that doped by the c onventional doping method, based on the Ba vacancy produced by the pre sent electro-substitution. The Ca doping mechanism in this system is d iscussed in detail.