Langbeinite-type Rb~2~Ca~2~(SO~4~)~3~
Boujelben, Mohamed; Toumi, Mohamed; Mhiri, Tahar; Acta Crystallographica Section E 63 (2007) i157–i157; doi:10.1107/S1600536807027043

data_2214416
_publ_section_title
;
 Langbeinite-type Rb~2~Ca~2~(SO~4~)~3~
;
_journal_coeditor_code           WM2116
_journal_issue                   7
_journal_name_full               'Acta Crystallographica Section E'
_journal_page_first              i157
_journal_page_last               i157
_journal_paper_doi               10.1107/S1600536807027043
_journal_volume                  63
_journal_year                    2007
_chemical_formula_iupac          'Rb2 Ca2 (S O4)3'
_chemical_formula_structural     'Rb2 (Ca2 S3 O12)'
_chemical_formula_sum            'Ca2 O12 Rb2 S3'
_chemical_formula_weight         539.28
_chemical_name_systematic
;
dirubidium dicalcium tris[sulfate(VI)]
;
_space_group_IT_number           198
_symmetry_cell_setting           cubic
_symmetry_space_group_name_Hall  'P 2ac 2ab 3'
_symmetry_space_group_name_H-M   'P 21 3'
_atom_sites_solution_primary     direct
_audit_creation_method           SHELXL-97
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   10.553(3)
_cell_length_b                   10.553(3)
_cell_length_c                   10.553(3)
_cell_measurement_reflns_used    23
_cell_measurement_temperature    293
_cell_measurement_theta_max      30.1
_cell_measurement_theta_min      2.7
_cell_volume                     1175.2(6)
_computing_cell_refinement       STADI4
_computing_data_collection       'STADI4 (Stoe & Cie, 2000)'
_computing_data_reduction        'X-RED (Stoe & Cie, 1996)'
_computing_molecular_graphics    'DIAMOND (Brandenburg & Berndt, 1999)'
_computing_publication_material  CRYSTALS
_computing_structure_refinement  'CRYSTALS (Betteridge <i>et al.</i>,  2003)'
_computing_structure_solution    'SHELXS97 (Sheldrick, 1997)'
_diffrn_ambient_temperature      298
_diffrn_measured_fraction_theta_full 0.986
_diffrn_measured_fraction_theta_max 0.986
_diffrn_measurement_device_type  'Stoe--Siemens AED2 four-circle'
_diffrn_measurement_method       \w/2\q
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_type           'Mo K\a'
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.08
_diffrn_reflns_limit_h_max       9
_diffrn_reflns_limit_h_min       -8
_diffrn_reflns_limit_k_max       10
_diffrn_reflns_limit_k_min       -10
_diffrn_reflns_limit_l_max       14
_diffrn_reflns_limit_l_min       -14
_diffrn_reflns_number            1236
_diffrn_reflns_theta_full        25.24
_diffrn_reflns_theta_max         29.89
_diffrn_reflns_theta_min         2.73
_diffrn_standards_decay_%        0.7
_diffrn_standards_interval_time  30
_diffrn_standards_number         2
_exptl_absorpt_coefficient_mu    9.791
_exptl_absorpt_correction_T_max  0.644
_exptl_absorpt_correction_T_min  0.231
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   '(MULABS in PLATON; Spek, 2003)'
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    3.048
_exptl_crystal_description       fragment
_exptl_crystal_F_000             1032
_exptl_crystal_size_max          0.22
_exptl_crystal_size_mid          0.132
_exptl_crystal_size_min          0.045
_refine_diff_density_max         0.927
_refine_diff_density_min         -1.000
_refine_ls_abs_structure_details 'Flack (1983), 558 Friedel pairs'
_refine_ls_abs_structure_Flack   0.00(4)
_refine_ls_extinction_coef       0.0008(5)
_refine_ls_extinction_method     SHELXL
_refine_ls_goodness_of_fit_ref   1.120
_refine_ls_matrix_type           full
_refine_ls_number_parameters     59
_refine_ls_number_reflns         1080
_refine_ls_number_restraints     0
_refine_ls_R_factor_all          0.1513
_refine_ls_R_factor_gt           0.0651
_refine_ls_shift/su_max          0.001
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
;
w=1/[\s^2^(Fo^2^)+(0.0210P)^2^+6.5703P] where P=(Fo^2^+2Fc^2^)/3
Method, part 1, Chebychev polynomial, (Watkin (1994).
Acta Cryst. A50, 411--437.
Prince (1982) Mathematical Techniques in Crystallography and
Materials Science. New York: Springer-Verlag.]
[weight] = 1.0/[A~0~*T~0~(x)+A~1~*T~1~(x) ... +A~n-1~]*T~n-1~(x)]
where A~i~ are the Chebychev coefficients listed below and x= Fcalc/Fmax
Method = Robust Weighting (Prince, 1982)
W = [weight] * [1-(deltaF/6*sigmaF)^2^]^2^
A~i~ are:
2.38 -2.95 2.50 -1.02 0.340
;
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_all         0.0349
_refine_ls_wR_factor_gt          0.1001
_refine_ls_wR_factor_ref         0.1278
_reflns_number_gt                658
_reflns_number_total             1080
_reflns_threshold_expression     I>3\s(I)
_cod_data_source_file            wm2116.cif
_cod_data_source_block           I
_cod_database_code               2214416
_cod_database_fobs_code          2214416