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Three Crystal Structures of Dehydrated $Cd^{2+}$ and $Rb^+$ Exchanged Zeolite A, $Cd_xRb_{12-2x}-A,$ x=4.0, 5.0 and 5.95

  • Song, Yeong-Sim (Department of Chemical Education, Pusan National University) ;
  • Kim, Un-Sik (Department of Chemistry, Pusan National University) ;
  • Kim, Yang (Department of Chemistry, Pusan National University) ;
  • Kim, Duk-Soo (Department of Chemistry, Cheju National University)
  • Published : 1990.08.20

Abstract

Three crystal structures of dehydrated Cd(II) and Rb(I) exchanged zeolite A, $Cd_{4.0}Rb_{4.0}-A (a = 12.204(3) {\AA}), Cd_{5.0}Rb_{2.0}-A (a = 12.202(1) {\AA}),$ and $Cd_{5.95}Rb_{0.1}-A (a = 12.250(2) {\AA}),$ have been determined by single-crystal X-ray diffraction techniques. Their structures were solved and refined in the cubic space group Pm3m at $21(1)^{\circ}C.$ All crystals were ion exchanged in flowing streams of mixed $Cd(NO_3)_2·4H_2O$ and $RbNO_3$ aqueous solution with total concentration of 0.05 M. All crystals were dehydrated at ca. $450^{\circ}C$ and $2×10^{-6}$ Torr for 2 days. In all of these structures, $Cd^{2+}$ ions are found on threefold axes, each nearly at the center of a 6-oxygen ring. The first three $Rb^+$ ions per unit cell preferentially associate with 8-oxygen rings, and additional $Rb^+$ ions, if present, are found on threefold axes in the large cavity. The final $R_1$ and $R_2$ values for the three structures are 0.087 and 0.079, 0.059 and 0.067, and 0.079 and 0.095, respectively.

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Cited by

  1. Framework-Type Determination for Zeolite Structures in the Inorganic Crystal Structure Database vol.39, pp.3, 1990, https://doi.org/10.1063/1.3432459