Crystal Chemistry of Yttrium-Barium-Copper Oxycarbonate Ceramics

  • Vatolin, Nikolay (Institute of Metallurgy, Ural Branch of Russian Academy of Sciences) ;
  • Dubrovina, Iring (Institute of Metallurgy, Ural Branch of Russian Academy of Sciences) ;
  • Balakirev, Viacimir (Institute of Metallurgy, Ural Branch of Russian Academy of Sciences) ;
  • Zubkov, Vladimir (Institute of Solid State Chemistry, Ural Branch of Russian Academy of Sciences) ;
  • Tyutyunik, Alexander (nstitute of Solid State Chemistry, Ural Branch of Russian Academy of Sciences)
  • Published : 2000.06.01

Abstract

The barium rich region of the Y-Ba-Cu-O-C system includes a tetragonal perovskite-like phase, which possesses a wide homogeneity region toward yttrium, copper and carbonate ion on the one hand, and toward oxygen, on the other hand. Accounting for vacancies ($\square$-vacancy) this phase could be described by the general formula per unit cell: {Ba$_8$}[Y$_{3-z}$Cu$_{5-x}$$(CO_3)_n$ $\square$$_{x+x-n}$]O$_{y{\pm}{\delta}y}$ (*). Here, cube-octahedral sites are represented in braces, while quasioctahedral ones with proper octahedral (Y, Cul), square (Cu2) and triangular (CO$_3$) configuration are shown in square brackets. The formula (*) was confirmed by full-profile Rietveld refinement based on X-ray diffraction data of YBa$_{5}$Cu$_2$O$_y$ (1-5-2 phase). Homogeneity region limits of the phase (*) at 96$0^{\circ}C$ in air were determined to be -0.33$\leq$x$\leq$1.80, 0.33$\leq$z$\leq$2.00, 0$\leq$n$\leq$3.

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References

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