On the Lamellar Compounds CuBiP2Se6, AgBiP2Se6 and AgBiP2S6. Antiferroelectric Phase Transitions Due to Cooperative Cu+ and Bi3+ Ion Motion
Matthew A. Gave; Daniel Bilc; S. D. Mahanti; Jean D. Breshears; Mercouri G. Kanatzidis; Inorganic Chemistry 44 (2005) 5293–5303; doi:10.1021/ic050357+

data_4327327
_publ_section_title
;
 On the Lamellar Compounds CuBiP2Se6, AgBiP2Se6 and AgBiP2S6.
 Antiferroelectric Phase Transitions Due to Cooperative Cu+ and Bi3+ Ion
 Motion
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_journal_name_full               'Inorganic Chemistry'
_journal_page_first              5293
_journal_page_last               5303
_journal_paper_doi               10.1021/ic050357+
_journal_volume                  44
_journal_year                    2005
_chemical_formula_sum            'Ag Bi P2 Se6'
_chemical_formula_weight         852.55
_chemical_name_systematic
; 
 ? 
;
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_symmetry_space_group_name_Hall  '-R 3'
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_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                90.00
_cell_angle_beta                 90.00
_cell_angle_gamma                120.00
_cell_formula_units_Z            6
_cell_length_a                   6.6524(13)
_cell_length_b                   6.6524(13)
_cell_length_c                   39.615(15)
_cell_measurement_temperature    293(2)
_cell_volume                     1518.3(7)
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      293(2)
_diffrn_measured_fraction_theta_full 0.998
_diffrn_measured_fraction_theta_max 0.998
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'fine-focus sealed tube'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0584
_diffrn_reflns_av_sigmaI/netI    0.0398
_diffrn_reflns_limit_h_max       7
_diffrn_reflns_limit_h_min       -7
_diffrn_reflns_limit_k_max       7
_diffrn_reflns_limit_k_min       -7
_diffrn_reflns_limit_l_max       43
_diffrn_reflns_limit_l_min       -43
_diffrn_reflns_number            3000
_diffrn_reflns_theta_full        23.22
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_diffrn_reflns_theta_min         1.54
_exptl_absorpt_coefficient_mu    41.116
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_exptl_crystal_F_000             2184
_refine_diff_density_max         1.494
_refine_diff_density_min         -1.576
_refine_diff_density_rms         0.375
_refine_ls_extinction_coef       0.00008(4)
_refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^
_refine_ls_extinction_method     SHELXL
_refine_ls_goodness_of_fit_ref   1.124
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     32
_refine_ls_number_reflns         498
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.124
_refine_ls_R_factor_all          0.0446
_refine_ls_R_factor_gt           0.0370
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0591P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
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_cod_data_source_file            ic0503572Bsi20050308_041727.cif
_cod_data_source_block           1mg19_4m
_cod_original_cell_volume        1518.2(7)
_cod_original_sg_symbol_H-M      'R -3'
_cod_database_code               4327327