Confinement-Driven Ferroelectricity in a Two-Dimensional Hybrid Lead Iodide Perovskite.
Chen, Xiao-Gang; Song, Xian-Jiang; Zhang, Zhi-Xu; Zhang, Han-Yue; Pan, Qiang; Yao, Jie; You, Yu-Meng; Xiong, Ren-Gen; Journal of the American Chemical Society 142 (2020) 10212–10218; doi:10.1021/jacs.0c03710

data_4134990
_publ_section_title
;
 Confinement-Driven Ferroelectricity in a Two-Dimensional Hybrid Lead
 Iodide Perovskite.
;
_journal_issue                   22
_journal_name_full               'Journal of the American Chemical Society'
_journal_page_first              10212
_journal_page_last               10218
_journal_paper_doi               10.1021/jacs.0c03710
_journal_volume                  142
_journal_year                    2020
_chemical_formula_moiety         'I4 Pb, 2(C6 H12 F2 N) '
_chemical_formula_sum            'C12 H24 F4 I4 N2 Pb'
_chemical_formula_weight         987.13
_space_group_crystal_system      orthorhombic
_space_group_IT_number           44
_space_group_name_Hall           'I 2 -2'
_space_group_name_H-M_alt        'I m m 2'
_atom_sites_solution_hydrogens   difmap
_audit_creation_method           SHELXL-2014/7
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_formula_units_Z            2
_cell_length_a                   27.464(9)
_cell_length_b                   6.5518(10)
_cell_length_c                   6.5518(10)
_cell_measurement_reflns_used    1164
_cell_measurement_temperature    423(2)
_cell_measurement_theta_max      26.3660
_cell_measurement_theta_min      3.1670
_cell_volume                     1178.9(5)
_computing_structure_refinement  'SHELXL-2014/7 (Sheldrick, 2014)'
_diffrn_ambient_temperature      423(2)
_diffrn_measured_fraction_theta_full 0.995
_diffrn_measured_fraction_theta_max 0.995
_diffrn_measurement_device_type  'XtaLAB Synergy R, DW system, HyPix'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.1259
_diffrn_reflns_av_unetI/netI     0.1111
_diffrn_reflns_Laue_measured_fraction_full 0.995
_diffrn_reflns_Laue_measured_fraction_max 0.995
_diffrn_reflns_limit_h_max       28
_diffrn_reflns_limit_h_min       -32
_diffrn_reflns_limit_k_max       7
_diffrn_reflns_limit_k_min       -7
_diffrn_reflns_limit_l_max       7
_diffrn_reflns_limit_l_min       -7
_diffrn_reflns_number            3406
_diffrn_reflns_point_group_measured_fraction_full 0.997
_diffrn_reflns_point_group_measured_fraction_max 0.997
_diffrn_reflns_theta_full        24.979
_diffrn_reflns_theta_max         24.979
_diffrn_reflns_theta_min         2.967
_diffrn_source                   'Rotating-anode X-ray tube'
_exptl_absorpt_coefficient_mu    12.421
_exptl_absorpt_correction_T_max  0.045
_exptl_absorpt_correction_T_min  0.034
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details
;
CrysAlisPro 1.171.40.14e (Rigaku Oxford Diffraction, 2018)
Empirical absorption correction using spherical harmonics,
 implemented in SCALE3 ABSPACK scaling algorithm.
;
_exptl_crystal_colour            red
_exptl_crystal_density_diffrn    2.781
_exptl_crystal_description       sheet
_exptl_crystal_F_000             880
_exptl_crystal_size_max          0.3
_exptl_crystal_size_mid          0.27
_exptl_crystal_size_min          0.25
_refine_diff_density_max         4.553
_refine_diff_density_min         -2.534
_refine_diff_density_rms         0.603
_refine_ls_abs_structure_details
;
 Refined as an inversion twin.
;
_refine_ls_abs_structure_Flack   0.52(3)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.585
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     93
_refine_ls_number_reflns         1156
_refine_ls_number_restraints     160
_refine_ls_restrained_S_all      1.486
_refine_ls_R_factor_all          0.2239
_refine_ls_R_factor_gt           0.1715
_refine_ls_shift/su_max          0.012
_refine_ls_shift/su_mean         0.003
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w=1/[\s^2^(Fo^2^)+(0.2000P)^2^] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.4511
_refine_ls_wR_factor_ref         0.4769
_reflns_Friedel_coverage         0.830
_reflns_Friedel_fraction_full    0.998
_reflns_Friedel_fraction_max     0.998
_reflns_number_gt                591
_reflns_number_total             1156
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            ja0c03710_si_009.cif
_cod_data_source_block           IMM2
_cod_depositor_comments
;Adding full bibliography for 4134988--4134996.cif.

 Adding full bibliography for 4134988--4134996.cif.
;
_cod_original_formula_sum        'C12 H24 F4 I4 N2 Pb '
_cod_database_code               4134990
_shelx_shelxl_version_number     2014/7
_shelx_res_checksum              3145
_shelx_hkl_checksum              81940