Reinvestigation of the structure of BaCuSi~2~O~6~ – evidence for a phase transition at high temperature
Sparta, Karine M.; Roth, Georg; Acta Crystallographica Section B 60 (2004) 491–495; doi:10.1107/S0108768104011644

data_2102630
_publ_section_title
;
 Reinvestigation of the structure of BaCuSi~2~O~6~ -- evidence for a
 phase transition at high temperature
;
_journal_issue                   5
_journal_name_full               'Acta Crystallographica Section B'
_journal_page_first              491
_journal_page_last               495
_journal_paper_doi               10.1107/S0108768104011644
_journal_volume                  60
_journal_year                    2004
_chemical_compound_source        Synthetic
_chemical_formula_moiety         'Cu O6 Si2, Ba'
_chemical_formula_sum            'Ba Cu O6 Si2'
_chemical_formula_weight         353.06
_chemical_name_common            'Barium copper cyclosilicate'
_chemical_name_systematic
;
 Barium copper cyclosilicate
;
_space_group_IT_number           139
_symmetry_cell_setting           tetragonal
_symmetry_space_group_name_Hall  '-I 4 2'
_symmetry_space_group_name_H-M   'I 4/m m m'
_atom_sites_solution_hydrogens   geom
_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                90.00
_cell_formula_units_Z            4
_cell_length_a                   7.1104(13)
_cell_length_b                   7.1104(13)
_cell_length_c                   11.175(3)
_cell_measurement_reflns_used    988
_cell_measurement_temperature    640(2)
_cell_measurement_theta_max      24.81
_cell_measurement_theta_min      3.40
_cell_volume                     565.0(2)
_computing_data_reduction        'STOE X-RED'
_computing_molecular_graphics    'ATOMS v5.1'
_computing_publication_material  'WinGX v1.64.05 (Farrugia, 1999)'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_database_code_amcsd             0018748
_diffrn_ambient_temperature      640(2)
_diffrn_measured_fraction_theta_full 1.000
_diffrn_measured_fraction_theta_max 1.000
_diffrn_measurement_device_type  'STOE IPDS'
_diffrn_measurement_method       'rotation method'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'fine-focus sealed tube'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71069
_diffrn_reflns_av_R_equivalents  0.0000
_diffrn_reflns_av_sigmaI/netI    0.0371
_diffrn_reflns_limit_h_max       8
_diffrn_reflns_limit_h_min       0
_diffrn_reflns_limit_k_max       8
_diffrn_reflns_limit_k_min       0
_diffrn_reflns_limit_l_max       13
_diffrn_reflns_limit_l_min       0
_diffrn_reflns_number            170
_diffrn_reflns_theta_full        24.81
_diffrn_reflns_theta_max         24.81
_diffrn_reflns_theta_min         3.40
_diffrn_standards_decay_%        0
_diffrn_standards_interval_count 0
_diffrn_standards_interval_time  0
_diffrn_standards_number         0
_exptl_absorpt_coefficient_mu    11.08
_exptl_absorpt_correction_T_max  0.1438
_exptl_absorpt_correction_T_min  0.0501
_exptl_absorpt_correction_type   numerical
_exptl_absorpt_process_details
'via equivalents using STOE X-SHAPE and X-RED (Stoe & Cie, 1996)'
_exptl_crystal_colour            purple
_exptl_crystal_density_diffrn    4.151
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       cuboid
_exptl_crystal_F_000             644
_exptl_crystal_size_max          0.27
_exptl_crystal_size_mid          0.24
_exptl_crystal_size_min          0.17
_refine_diff_density_max         0.525
_refine_diff_density_min         -0.508
_refine_ls_extinction_coef       0.0021(2)
_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   1.023
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     23
_refine_ls_number_reflns         170
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.023
_refine_ls_R_factor_all          0.0217
_refine_ls_R_factor_gt           0.0153
_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^)+(0.0000P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0249
_refine_ls_wR_factor_ref         0.0251
_reflns_number_gt                135
_reflns_number_total             170
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            na5017.cif
_cod_data_source_block           bcso640
_cod_database_code               2102630
_amcsd_formula_title             BaCuSi2O6