Publication
Nature
Paper

New double-sheet copper oxide compounds with BiO or TIO bilayers

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Abstract

ONE of the main families of oxide superconductors comprises compounds with varying numbers of CuO2 sheets sandwiched between BiO or TIO bilayers1-5. The superconducting transition temperature (Tc) in these compounds increases with the number of CuO2 sheets; for example, Tc is 80-108 K for the double-sheet 2212 phase, and 110-125 K for the triple-sheet 2223 phase. Here we describe a new family of double-sheet copper oxide compounds with BiO or TIO bilayers, which can improve our understanding of the relationship between Tc and the CuO2 sheets. The new compounds, Bi2Sr2(Ln1-xCex)2Cu 2O10+y, and Tl2Ba2(Ln1-xCex)2Cu 2O10+y (where Ln is Sm, Eu or Gd), have double CuO2 pyramidal sheets between double BiO or TIO layered units, like the 2212 phase, but with a different arrangement of adjacent CuO2 sheets. The new bismuth compounds (Bi-2222) have a significantly lower Tc (∼30 K or less) than the 2212 or 2223 phases, even when the charge-carrier (hole) concentrations are comparable. So far, we have not found superconductivity in the Tl-2222 compounds. © 1989 Nature Publishing Group.

Date

01 Jan 1989

Publication

Nature