Acta Phys. -Chim. Sin. ›› 1987, Vol. 3 ›› Issue (01): 35-41.doi: 10.3866/PKU.WHXB19870107

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REFINEMENT OF THE CRYSTAL STRUCTURE OF RbI03·2HI03 AND ITS CENTROSYMMETRIC DEGREE

Fu Zhengmin; Li Wenxiu; Dai Jinbi; Liang Dongcai   

  1. Institute of Physics; Academia Sinica
    Institute of Biophysics; Academia Sinica
  • Received:1985-07-26 Revised:1986-01-20 Published:1987-02-15

Abstract: The crystal structure of the compound RbIO_3·2HIO_3 has been redetermined by heavy-atom method and refined by full matrix least-squares method. The crystal belongs to triclinic system with cell dimensions; a=0.8332 nm, b=0.8232 nm, c=0.8264 nm; α=60.66°, β=85.80°, γ=66.10°. Z= 2, D_m = 4.61 g cm~(-3). The structure is non-centrosymmetric; nevertheless, it has a high degree of centrosymmetry, as a measurement of it, < |△r|>w=0.009 nm. The reliable factor is R=0.076.
Three O atoms are bound to each I atom with mean distance of about 0.18 nm forming a distorted IO_3~- triangular cone; in addition other three neighbour O atoms are bound to it with distances of 0.25—0.33 nm. These six O atoms and their centering I atom form a distorted IO_6 octahedron. Nine O atoms are bound to each Rb atom with distances of 0.286—0.351 nm forming a RbO_9 polyhedron.