ChemInform Abstract: Enhancement of Zero Resistance Temperature above 90 K and Hole Distribution in (Hg0.5Pb05)Sr2(Ca0.7Y0.3)Cu2O7‐δ via Chemical Substitution of Ba into Sr Sites.

Abstract

Enhancement of Zero Resistance Temperature above 90 K and Hole Distribution in (Hg0.5Pb05)Sr2(Ca0.7Y0.3)Cu2O7-δ via Chemical Substitution of Ba into Sr Sites.-In the series of superconducting (Hg0.5Pb0.5)(Sr2-xBax)(Ca0.7Y0.3) Cu2O7-δ compounds the zero resistance temp. increases from 78 K for x = 0 to 92.5 K for x = 0.2. According to the O K-edge and Cu L-edge XANES spectra for samples with 0 ≤ x ≤ 0.5, chemical substitution of Ba2+ for Sr2+ causes a decrease in the O 2p hole concentration within the out-of-plane oxygen sites. In the in-plane CuO2 layers, the hole concentration remains unchanged for 0 . ltoreq. x ≤ 0.2. Hence, the out-of-plane oxygen plays an important role in the control of the Tc value. -(LIU, R. S.; CHEN, J. M.; SHY, D. S.; Inorg.