High-pressure synthetic (Na~0.97~Mg~0.03~)(Mg~0.43~Fe~0.17~^3+^Si~0.40~)Si~2~O~6~, with six-coordinated silicon, isostructural with <i>P</i>2/<i>n</i> omphacite
Posner, Esther S.; Konzett, Jürgen; Frost, Daniel J.; Downs, Robert T.; Yang, Hexiong; Acta Crystallographica Section E 68 (2012) i18–; doi:10.1107/S1600536812002966

data_2233440
_publ_section_title
;
 High-pressure synthetic
 (Na~0.97~Mg~0.03~)(Mg~0.43~Fe~0.17~^3+^Si~0.40~)Si~2~O~6~, with
 six-coordinated silicon, isostructural with <i>P</i>2/<i>n</i> omphacite
;
_journal_coeditor_code           FJ2504
_journal_issue                   2
_journal_name_full               'Acta Crystallographica Section E'
_journal_page_first              i18
_journal_paper_doi               10.1107/S1600536812002966
_journal_volume                  68
_journal_year                    2012
_chemical_formula_iupac
'(Na0.97 Mg0.03) (Mg0.43 Fe0.17 Si0.40) Si2 O6'
_chemical_formula_sum            'Fe0.17 Mg0.46 Na0.97 O6 Si2.4'
_chemical_formula_weight         206.39
_chemical_name_systematic
;
(sodium magnesium) [magnesium iron(III) silicon] disilicate
;
_space_group_IT_number           13
_symmetry_cell_setting           monoclinic
_symmetry_space_group_name_Hall  '-P 2yac'
_symmetry_space_group_name_H-M   'P 1 2/n 1'
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                90.00
_cell_angle_beta                 108.003(6)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   9.4432(8)
_cell_length_b                   8.6457(7)
_cell_length_c                   5.2540(5)
_cell_measurement_reflns_used    1071
_cell_measurement_temperature    293(2)
_cell_measurement_theta_max      35.60
_cell_measurement_theta_min      3.25
_cell_volume                     407.95(6)
_computing_cell_refinement       'SAINT (Bruker, 2004)'
_computing_data_collection       'APEX2 (Bruker, 2004)'
_computing_data_reduction        'SAINT (Bruker, 2004)'
_computing_molecular_graphics    'XtalDraw (Downs & Hall-Wallace, 2003)'
_computing_publication_material  'publCIF (Westrip, 2010)'
_computing_structure_refinement  'SHELXL97 (Sheldrick, 2008)'
_computing_structure_solution    'SHELXS97 (Sheldrick, 2008)'
_diffrn_ambient_temperature      293(2)
_diffrn_measured_fraction_theta_full 0.997
_diffrn_measured_fraction_theta_max 0.997
_diffrn_measurement_device_type  'Bruker APEXII CCD area-detector'
_diffrn_measurement_method       '\f and \w scan'
_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  0.0332
_diffrn_reflns_av_sigmaI/netI    0.0331
_diffrn_reflns_limit_h_max       14
_diffrn_reflns_limit_h_min       -14
_diffrn_reflns_limit_k_max       10
_diffrn_reflns_limit_k_min       -13
_diffrn_reflns_limit_l_max       7
_diffrn_reflns_limit_l_min       -7
_diffrn_reflns_number            6586
_diffrn_reflns_theta_full        32.57
_diffrn_reflns_theta_max         32.51
_diffrn_reflns_theta_min         3.27
_exptl_absorpt_coefficient_mu    1.687
_exptl_absorpt_correction_T_max  0.9204
_exptl_absorpt_correction_T_min  0.9055
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   '(SADABS; Sheldrick 2005)'
_exptl_crystal_colour            'pale gray'
_exptl_crystal_density_diffrn    3.360
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       cube
_exptl_crystal_F_000             409
_exptl_crystal_size_max          0.06
_exptl_crystal_size_mid          0.05
_exptl_crystal_size_min          0.05
_refine_diff_density_max         0.507
_refine_diff_density_min         -0.661
_refine_ls_extinction_coef       0
_refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^
_refine_ls_extinction_method     'SHELXL97 (Sheldrick, 2008)'
_refine_ls_goodness_of_fit_ref   1.065
_refine_ls_matrix_type           full
_refine_ls_number_parameters     96
_refine_ls_number_reflns         1481
_refine_ls_number_restraints     3
_refine_ls_restrained_S_all      1.064
_refine_ls_R_factor_all          0.0661
_refine_ls_R_factor_gt           0.0356
_refine_ls_shift/su_max          0.001
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0264P)^2^+0.6629P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0735
_refine_ls_wR_factor_ref         0.0851
_reflns_number_gt                980
_reflns_number_total             1481
_reflns_threshold_expression     I>2sigma(I)
_cod_data_source_file            fj2504.cif
_cod_data_source_block           I
_cod_original_sg_symbol_H-M      'P 2/n'
_cod_original_formula_sum        'Fe0.17 Mg0.46 Na0.97 O6 Si2.40'
_cod_database_code               2233440
_cod_database_fobs_code          2233440