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#$Date: 2008-01-14 00:15:36 +0200 (Mon, 14 Jan 2008) $
#$Revision: 14 $
#$URL: file:///home/coder/svn-repositories/cod/cif/1/1000339.cif $
#------------------------------------------------------------------------------
#
# This file is available in the Crystallography Open Database (COD),
# http://www.crystallography.net/
#
# All data on this site have been placed in the public domain by the
# contributors.
#
data_1000339
_chemical_name_systematic
;
Dipotassium bis(oxoniobium) cyclo-tetrasilicate
;
_chemical_formula_structural       'K2 (Nb O)2 (Si4 O12)'
_chemical_formula_sum              'K2 Nb2 O14 Si4'
_publ_section_title
;
The potassium niobyl cyclotetrasilicate K~2~(NbO)~2~Si~4~O~12~
;
loop_
_publ_author_name
  'Crosnier, M P'
  'Guyomard, D'
  'Verbaere, A'
  'Piffard, Y'
  'Tournoux, M'
_journal_name_full                 'Journal of Solid State Chemistry'
_journal_coden_ASTM                JSSCBI
_journal_volume                    98
_journal_year                      1992
_journal_page_first                128
_journal_page_last                 132
_cell_length_a                     8.7404(8)
_cell_length_b                     8.7404(8)
_cell_length_c                     8.136(1)
_cell_angle_alpha                  90
_cell_angle_beta                   90
_cell_angle_gamma                  90
_cell_volume                       621.5
_cell_formula_units_Z              2
_symmetry_space_group_name_H-M     'P 4 b m'
_symmetry_Int_Tables_number        100
_symmetry_cell_setting             tetragonal
loop_
_symmetry_equiv_pos_as_xyz
  'x,y,z'
  '-x,-y,z'
  '1/2+x,1/2-y,z'
  '1/2-x,1/2+y,z'
  '-y,x,z'
  'y,-x,z'
  '1/2+y,1/2+x,z'
  '1/2-y,1/2-x,z'
loop_
_atom_type_symbol
_atom_type_oxidation_number
  Nb5+   5.000
  K1+    1.000
  Si4+   4.000
  O2-   -2.000
loop_
_atom_site_label
_atom_site_type_symbol
_atom_site_symmetry_multiplicity
_atom_site_Wyckoff_symbol
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
_atom_site_occupancy
_atom_site_attached_hydrogens
_atom_site_calc_flag
  Nb1   Nb5+   2 a 0. 0. 0.2160(2) 1.  0 d
  Nb2   Nb5+   2 a 0. 0. 0.7194(2) 1.  0 d
  K1    K1+    4 c 0.3226(1) 0.8226(1) 0.9919(3) 1.  0 d
  Si1   Si4+   4 c 0.1242(2) 0.6242(2) 0.3015(2) 1.  0 d
  Si2   Si4+   4 c 0.1240(2) 0.6240(2) 0.6938(2) 1.  0 d
  O1    O2-    8 d 0.4251(4) 0.2882(4) 0.2330(4) 1.  0 d
  O2    O2-    8 d 0.4219(5) 0.2892(5) 0.7654(5) 1.  0 d
  O3    O2-    2 a 0. 0. 0. 1.  0 d
  O4    O2-    2 a 0. 0. 0.5010(9) 1.  0 d
  O5    O2-    4 c 0.1200(4) 0.6200(4) 0.4968(9) 1.  0 d
  O6    O2-    2 b 0.5 0. 0.228(1) 1.  0 d
  O7    O2-    2 b 0.5 0. 0.7628(8) 1.  0 d
loop_
_atom_site_aniso_label
_atom_site_aniso_U_11
_atom_site_aniso_U_12
_atom_site_aniso_U_13
_atom_site_aniso_U_22
_atom_site_aniso_U_23
_atom_site_aniso_U_33
  Nb1   0.0071(1) 0. 0. 0.0071(1) 0. 0.0079(2)
  Nb2   0.0064(1) 0. 0. 0.0064(1) 0. 0.0079(2)
  K1    0.0180(4) -0.0034(5) 0.0005(5) 0.0180(4) 0.0005(5) 0.0124(6)
  Si1   0.0076(4) 0.0007(7) 0.0004(5) 0.0076(4) 0.0004(5) 0.0039(6)
  Si2   0.0071(4) -0.0001(6) -0.0003(5) 0.0071(4) -0.0003(5) 0.0036(7)
_refine_ls_R_factor_all            0.021