The trigonal polymorph of strontium tetraborate, β-SrB~4~O~7~
Vasiliev, Alexander D.; Cherepakhin, Alexander V.; Zaitsev, Alexander I.; Acta Crystallographica Section E 66 (2010) i48–; doi:10.1107/S1600536810019069

data_2226327
_publ_section_title
;
 The trigonal polymorph of strontium tetraborate, \b-SrB~4~O~7~
;
_journal_coeditor_code           WM2345
_journal_issue                   6
_journal_name_full               'Acta Crystallographica Section E'
_journal_page_first              i48
_journal_paper_doi               10.1107/S1600536810019069
_journal_volume                  66
_journal_year                    2010
_chemical_formula_iupac          'Sr B4 O7'
_chemical_formula_moiety         'B4 O7, Sr'
_chemical_formula_structural     'Sr (B4 O7)'
_chemical_formula_sum            'B4 O7 Sr'
_chemical_formula_weight         242.86
_chemical_name_common            'Strontium tetraborate'
_chemical_name_systematic
;
strontium tetraborate
;
_space_group_IT_number           143
_symmetry_cell_setting           trigonal
_symmetry_space_group_name_Hall  'P 3'
_symmetry_space_group_name_H-M   'P 3'
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_cell_angle_alpha                90.00
_cell_angle_beta                 90.00
_cell_angle_gamma                120.00
_cell_formula_units_Z            9
_cell_length_a                   17.1450(10)
_cell_length_b                   17.1450(10)
_cell_length_c                   4.2527(5)
_cell_measurement_reflns_used    2820
_cell_measurement_temperature    296(2)
_cell_measurement_theta_max      29.30
_cell_measurement_theta_min      2.38
_cell_volume                     1082.61(16)
_computing_cell_refinement       'SAINT-<i>Plus</i> (Bruker, 2001)'
_computing_data_collection       'SMART (Bruker, 2001)'
_computing_data_reduction        'SAINT-<i>Plus</i> (Bruker, 2001)'
_computing_molecular_graphics    'SHELXTL (Sheldrick, 2008)'
_computing_publication_material  'SHELXTL (Sheldrick, 2008)'
_computing_structure_refinement  'SHELXTL (Sheldrick, 2008)'
_computing_structure_solution    'SHELXTL (Sheldrick, 2008)'
_diffrn_ambient_temperature      296(2)
_diffrn_measured_fraction_theta_full 0.997
_diffrn_measured_fraction_theta_max 0.997
_diffrn_measurement_device_type  'Bruker SMART CCD area-detector'
_diffrn_measurement_method       '\f and \w'
_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  0.0539
_diffrn_reflns_av_sigmaI/netI    0.0780
_diffrn_reflns_limit_h_max       23
_diffrn_reflns_limit_h_min       -22
_diffrn_reflns_limit_k_max       23
_diffrn_reflns_limit_k_min       -23
_diffrn_reflns_limit_l_max       5
_diffrn_reflns_limit_l_min       -5
_diffrn_reflns_number            10350
_diffrn_reflns_theta_full        28.72
_diffrn_reflns_theta_max         28.72
_diffrn_reflns_theta_min         2.38
_exptl_absorpt_coefficient_mu    11.185
_exptl_absorpt_correction_T_max  0.2422
_exptl_absorpt_correction_T_min  0.0949
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   '(SADABS; Sheldrick, 2004)'
_exptl_crystal_colour            colorless
_exptl_crystal_density_diffrn    3.3526(5)
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       ellipsoidal
_exptl_crystal_F_000             1026
_exptl_crystal_size_max          0.40
_exptl_crystal_size_mid          0.25
_exptl_crystal_size_min          0.18
_refine_diff_density_max         1.018
_refine_diff_density_min         -0.492
_refine_ls_abs_structure_details 'Flack (1983), 1836 Friedel pairs'
_refine_ls_abs_structure_Flack   -0.030(7)
_refine_ls_extinction_coef       0.0794(13)
_refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^
_refine_ls_extinction_method     'SHELXTL (Sheldrick, 2008)'
_refine_ls_goodness_of_fit_ref   0.849
_refine_ls_matrix_type           full
_refine_ls_number_parameters     265
_refine_ls_number_reflns         3709
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      0.849
_refine_ls_R_factor_all          0.0399
_refine_ls_R_factor_gt           0.0304
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w=1/[\s^2^(Fo^2^)+(0.0000P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0606
_refine_ls_wR_factor_ref         0.0640
_reflns_number_gt                3202
_reflns_number_total             3709
_reflns_threshold_expression     I>2\s(I)
_cod_data_source_file            wm2345.cif
_cod_data_source_block           I
_cod_original_formula_sum        'B4 O7 Sr1'
_cod_database_code               2226327
_cod_database_fobs_code          2226327