#------------------------------------------------------------------------------
#$Date: 2010-01-30 15:59:17 +0200 (Sat, 30 Jan 2010) $
#$Revision: 966 $
#$URL: file:///home/coder/svn-repositories/cod/cif/1/1001720.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_1001720
_chemical_name_systematic          'Barium niobate silicate *'
_chemical_name_mineral             'Belkovite'
_chemical_formula_structural       'Ba3 Nb6 Si4 O26'
_chemical_formula_sum              'Ba3 Nb6 O26 Si4'
_publ_section_title
;
De nouveaux oxydes a reseau forme d'octaedres Nb O6 (Ta O6) et de
groupes Si2 O7: Les phases A3 Ta6 Si4 O26 (A= Ba, Sr) et K6 M6 Si4 O26
(M= Nb, Ta)
;
loop_
_publ_author_name
  'Choisnet, J'
  'Nguyen, N'
  'Groult, D'
  'Raveau, B'
_journal_name_full                 'Materials Research Bulletin'
_journal_coden_ASTM                MRBUAC
_journal_volume                    11
_journal_year                      1976
_journal_page_first                887
_journal_page_last                 894
_cell_length_a                     8.981
_cell_length_b                     8.981
_cell_length_c                     7.84
_cell_angle_alpha                  90
_cell_angle_beta                   90
_cell_angle_gamma                  120
_cell_volume                       547.6
_cell_formula_units_Z              1
_exptl_crystal_density_meas        4.56
_symmetry_space_group_name_H-M     'P -6 2 m'
_symmetry_Int_Tables_number        189
_symmetry_cell_setting             hexagonal
loop_
_symmetry_equiv_pos_as_xyz
  'x,y,z'
  '-y,x-y,z'
  'y-x,-x,z'
  'x,y,-z'
  '-y,x-y,-z'
  'y-x,-x,-z'
  'y,x,z'
  'x-y,-y,z'
  '-x,y-x,z'
  'y,x,-z'
  'x-y,-y,-z'
  '-x,y-x,-z'
loop_
_atom_type_symbol
_atom_type_oxidation_number
  Ba2+   2.000
  Nb5+   5.000
  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
  Ba1   Ba2+   3 g 0.593 0. 0.5 1.  0 d
  Nb1   Nb5+   6 i 0.238 0. 0.239 1.  0 d
  Si1   Si4+   4 h 0.3333 0.6667 0.203 1.  0 d
  O1    O2-    2 c 0.3333 0.6667 0. 1.  0 d
  O2    O2-    3 f 0.273 0. 0. 1.  0 d
  O3    O2-    6 i 0.819 0. 0.236 1.  0 d
  O4    O2-   12 l 0.489 0.183 0.284 1.  0 d
  O5    O2-    3 g 0.227 0. 0.5 1.  0 d
_refine_ls_R_factor_all            0.046
_cod_database_code 1001720