Effects of low-level Ag doping on Bi(sub 2)Sr(sub 2)CaCu(sub 2)O(sub 8+x)

摘要

Bi(sub 2)Sr(sub 2)CaCu(sub 2)O(sub 8) has been doped with silver, up to 10,000 ppm, in three ways: excess additions, substitution of Ag for Bi, and substitution of Ag for Sr. Effects of doping on the c-axis lattice parameter and critical temperature ((Tc)) were measured. Effects from doing were only observed in slow-cooled (10(degree)/hr) oxygen equilibrated samples. Doping by excess additions caused a small decrease in (Tc) and an increase in the c-axis length of the lattice. Doping by substitution, compared to excess Ag additions, caused a larger decrease in (Tc) and higher c-axis values for doping levels up to 1,000 ppm. Doping by substitution at higher levels (1,000--10,000 ppm) caused (Tc) to increase and the c-axis to decrease. Samples with similar substitutional doping levels exhibited comparable (Tc) values and samples with Ag substituted for Sr consistently exhibited higher c-axis values than samples that had equivalent amounts of Ag substituted for Bi.