a1 AT&T Bell Laboratories, Murray Hill, New Jersey 07974-0636
Electrochemical and high pressure oxygenation experiments are described which extend the range of intercalated oxygen content beyond that accessible in 1 atm O2 treatments for the triangular planar cuprate delafossites YCuO2+x and LaCuO2+x, with the intention of increasing the hole doping, and filling vacancies in the intercalated oxygen lattice to decrease electrical resistivities. Stabilization of the 2H polytype of YCuO2 through 1% Ca substitution for Y and oxidation conditions for obtaining the pure orthorhombic intercalated oxygen superlattice form of YCuO2.50 are also described. Temperature dependent resistivities for some of the superoxygenated compositions are reported; metallic behavior was not observed.
(Received May 17 1993)
(Accepted September 17 1993)