Structures of the superconducting oxides<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Tl</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Ba</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>Cu<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:mrow><mml:mn>6</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Bi</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Sr</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>Cu<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:mrow><mml:mn>6</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>

C.C. Torardi(Experimental Station), M.A. Subramanian(DuPont (United States)), J. C. CALABRESE(DuPont (United States)), J. Gopalakrishnan(DuPont (United States)), E. M. McCarron(DuPont (United States)), K. J. Morrissey(DuPont (United States)), T.R. Askew(Experimental Station), R. B. Flippen(DuPont (United States)), U. Chowdhry(Experimental Station), A.W. Sleight(DuPont (United States))
Physical review. B, Condensed matter
July 1, 1988
10.1103/physrevb.38.225
Cited by 414

Abstract

The structures of ${\mathrm{Tl}}_{2}$${\mathrm{Ba}}_{2}$Cu${\mathrm{O}}_{6}$ and ${\mathrm{Bi}}_{2}$${\mathrm{Sr}}_{2}$Cu${\mathrm{O}}_{6}$ have been solved and refined from single-crystal x-ray diffraction data. The structures are essentially the same and have single Cu-O sheets separated by either Tl-O or Bi-O double layers. The ${\mathrm{Tl}}_{2}$${\mathrm{Ba}}_{2}$Cu${\mathrm{O}}_{6}$ structure is tetragonal with $a=3.87$ \AA{} and $c=23.24$ \AA{}, and there are strictly flat Cu-O sheets. ${\mathrm{Bi}}_{2}$${\mathrm{Sr}}_{2}$Cu${\mathrm{O}}_{6}$ has a lower-symmetry structure which may be approximated with an orthorhombic cell with $a=5.36$ \AA{}, $b=5.37$ \AA{}, and $c=24.62$ \AA{}; however, this ignores superstructure reflections along both the $a$ and $c$ axes. The Tl-O layers are much more strongly bound to each other than are the Bi-O layers; thus, better conduction along the $c$ axis is expected for ${\mathrm{Tl}}_{2}$${\mathrm{Ba}}_{2}$Cu${\mathrm{O}}_{6}$ relative to ${\mathrm{Bi}}_{2}$${\mathrm{Sr}}_{2}$Cu${\mathrm{O}}_{6}$. Superconducting transition temperatures of 9 and 90 K were observed for ${\mathrm{Bi}}_{2}$${\mathrm{Sr}}_{2}$Cu${\mathrm{O}}_{6}$ and ${\mathrm{Tl}}_{2}$${\mathrm{Ba}}_{2}$Cu${\mathrm{O}}_{6}$, respectively.

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