A NEW ELECTROCHEMICAL DOPING METHOD USING M-BETA''-AL2O3 IONIC CONDUCTORS

摘要

Electrochemical cation doping (M(n+)) into oxide ceramics was carried out at low temperature (400-600 degrees C) using the sandwich electrolysis system, (+)Ag/M-beta ''-Al2O3//oxide ceramics//M-beta ''- -Al2O3/Ag(-), where M-beta ''-Al2O3 is a M(n+) ionic conductor that blocks electron and oxygen anion migration in the system. Various cations (Na+, K+, Ag+, Ca2+, Sr2+, Zn2+) were doped together with substitution for Ba2+, when the YBa2Cu3Oy (YBCO) superconductor was used as the oxide ceramics. The doping occurred only in the grain boundaries of the ceramics at low electrolysis current or voltage. Under high current or voltage, only Ca2+ was doped into the bulk, while the other cations were doped into the grain boundaries together with destruction of the YBCO. Thus, this is a new method for selective cation doping into oxide ceramics, especially at the grain boundaries. (C) 1997 Academic Press. [References: 10]