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#$Date: 2009-11-14 14:09:05 +0100 (Sat, 14 Nov 2009) $
#$Revision: 846 $
#$URL: svn://www.crystallography.net/cod/cif/2/2003077.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_2003077
_journal_name_full               'Acta Crystallographica, Section B'
_journal_volume                  55
_journal_year     1999
_journal_page_first     157
_journal_page_last     164
_publ_section_title
;
Solution and Refinement of the Structure of Bi7Ta3O18 Using Single-Crystal
X-ray and Powder Neutron Diffraction Data
;
loop_
    _publ_author_name
    'Ling, C. D.'
    'Schmid, S.'
    'Withers, R. L.'
    'Thompson, J. G.'
    'Ishizawa, N.'
    'Kishimoto, S'
_chemical_name_systematic
;
bismuth tantalum oxide
;
_chemical_name_common     ?
_chemical_formula_moiety     ?
_chemical_formula_sum     'Bi7 Ta3 O18'
_chemical_formula_structural     ?
_chemical_formula_analytical     ?
_chemical_formula_weight     2293.71
_chemical_melting_point     ?
_symmetry_cell_setting     monoclinic
_symmetry_space_group_name_H-M     'C 2/m'
_symmetry_space_group_name_Hall     ?
loop_
    _symmetry_equiv_pos_as_xyz
    +x,+y,+z
    -x,+y,-z
    -x,-y,-z
    +x,-y,+z
    +x+1/2,+y+1/2,+z
    -x+1/2,+y+1/2,-z
    -x+1/2,-y+1/2,-z
    +x+1/2,-y+1/2,+z
_cell_length_a     34.0084(9)
_cell_length_b     7.6069(2)
_cell_length_c     6.63644(17)
_cell_angle_alpha     90.0
_cell_angle_beta     109.2375(11)
_cell_angle_gamma     90.0
_cell_volume     1620.94(7)
_cell_formula_units_Z     4
_cell_measurement_temperature     293
_exptl_absorpt_coefficient_mu     ?
_exptl_absorpt_correction_T_min     ?
_exptl_absorpt_correction_T_max     ?
_diffrn_ambient_temperature     293
_diffrn_radiation_type     neutron
_diffrn_radiation_wavelength     ?
_diffrn_radiation_source     'spallation'
_diffrn_radiation_monochromator     ?
_diffrn_measurement_device     '3He gas and ZnS scintillation counters'
_diffrn_measurement_method     'time-of-flight'
_refine_ls_structure_factor_coef     ?
_refine_ls_matrix_type     ?
_refine_ls_R_factor_all     ?
_refine_ls_goodness_of_fit_all     5.41
_refine_ls_restrained_S_all     ?
_refine_ls_restrained_S_obs     ?
_refine_ls_number_parameters     116
_refine_ls_number_restraints     ?
_refine_ls_number_constraints     ?
_refine_ls_hydrogen_treatment     ?
_refine_ls_weighting_scheme     ?
_refine_ls_shift/esd_max     ?
_refine_ls_shift/esd_mean     ?
_refine_ls_extinction_method     ?
_refine_ls_extinction_coef     ?
_refine_ls_abs_structure_details     ?
_refine_ls_abs_structure_Flack     ?
loop_
    _atom_type_symbol
    _atom_type_description
    _atom_type_scat_dispersion_real
    _atom_type_scat_dispersion_imag
    _atom_type_scat_source
    Bi ? -9.511 4.206 Int._Tables_Vol_IV_Tables_2.2B_and_2.3.1
    Ta ? -3.946 10.597 Int._Tables_Vol_IV_Tables_2.2B_and_2.3.1
    O ? .015015 .012024 Int._Tables_Vol_IV_Tables_2.2B_and_2.3.1
loop_
    _atom_site_label
    _atom_site_fract_x
    _atom_site_fract_y
    _atom_site_fract_z
    _atom_site_U_iso_or_equiv
    _atom_site_thermal_displace_type
    _atom_site_occupancy
    Bi1 .24592(12) .5 .4693(6) .0114(7) Uiso 1.0
    Bi2 .14509(7) .2522(4) .4641(3) .0154(5) Uiso 1.0
    Bi3 .14788(9) .5 .9794(5) .0019(6) Uiso 1.0
    Ta4 .05535(7) .2490(3) .9919(4) .0011(4) Uiso 1.0
    Bi5 .04985(10) .5 .4544(6) .0234(11) Uiso 1.0
    Ta6 .25 .25 .0 .0032(8) Uiso 1.0
    Bi7 .16126(10) .0 .0205(5) .0119(6) Uiso 1.0
    Bi8 .05314(9) .0 .5117(5) .0043(6) Uiso 1.0
    O9 .07053(12) .5 .0872(5) .0016(8) Uiso 1.0
    O10 .11913(9) .2017(4) .0979(5) .0085(7) Uiso 1.0
    O11 .04957(9) .2973(4) .7019(4) .0064(6) Uiso 1.0
    O12 .07096(9) .2109(5) .3232(5) .0106(7) Uiso 1.0
    O13 .04746(14) .0 .9260(7) .0098(10) Uiso 1.0
    O14 .0 .2889(5) .0 .0026(7) Uiso 1.0
    O15 .23936(13) .2937(7) .6883(7) .0436(13) Uiso 1.0
    O16 .23930(15) .0 .9454(8) .0140(10) Uiso 1.0
    O17 .16979(15) .5 .3363(8) .0131(10) Uiso 1.0
    O18 .18926(11) .2898(5) .9466(6) .0223(9) Uiso 1.0
    O19 .11791(16) .0 .6697(8) .0206(12) Uiso 1.0
    O20 .11376(13) .5 .5550(7) .0035(8) Uiso 1.0
    O21 .18336(13) .0 .3733(7) .0086(8) Uiso 1.0