ISSN:
1573-4803
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract T c data are reported for powders of cation-stoichiometric Bi2Sr2CaCu2Oδ and for nonstoichiometric samples based on the three mechanisms Bi⇄Sr, Sr⇄Ca and Sr vacancy. For each, the T c values depend critically on the final oxygen contents, which were varied by heating samples in either O2 or N2 at different temperatures. Stoichiometric Bi2Sr2CaCu2Oδ has the highest T c, 92 K, obtained after heating in O2 at ∼ 820 °C. Heating in O2 at lower temperatures gives rise to overdoping and T c decreases to 60 K. The other cation compositions show a smaller maximum T c but also less reduction in T c on overdoping. Under-doped samples, with reduced T c values were obtained on heating in N2. These data, together with selected literature results, lead to a unified picture of the variation of T c with cation composition and oxygen content.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00349639
