Crystal structure across the β to α phase transition in thermoelectric Cu<sub>2-<i>x</i></sub> Se.
Eikeland, Espen; Blichfeld, Anders B.; Borup, Kasper A.; Zhao, Kunpeng; Overgaard, Jacob; Shi, Xun; Chen, Lidong; Iversen, Bo B.; IUCrJ 4 (2017) 476–485; doi:10.1107/S2052252517005553

data_1556755
_publ_section_title
;
 Crystal structure across the \b to \a phase transition in thermoelectric
 Cu<sub>2-<i>x</i></sub> Se.
;
_journal_coeditor_code           LC5071SUP1
_journal_issue                   'Pt 4'
_journal_name_full               IUCrJ
_journal_page_first              476
_journal_page_last               485
_journal_paper_doi               10.1107/S2052252517005553
_journal_volume                  4
_journal_year                    2017
_chemical_formula_moiety         '0.33(Cu5.66 Se3)'
_chemical_formula_sum            'Cu1.89 Se'
_chemical_formula_weight         198.94
_space_group_crystal_system      trigonal
_space_group_IT_number           166
_space_group_name_Hall           '-R 3 2"'
_space_group_name_H-M_alt        'R -3 m :H'
_atom_sites_solution_primary     direct
_audit_creation_date             2016-11-28
_audit_creation_method
;
Olex2 1.2
(compiled 2016.11.07 svn.r3353 for OlexSys, GUI svn.r5261)
;
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                120
_cell_formula_units_Z            6
_cell_length_a                   4.1019(16)
_cell_length_b                   4.1019(16)
_cell_length_c                   20.533(9)
_cell_measurement_reflns_used    154
_cell_measurement_temperature    99.99(14)
_cell_measurement_theta_max      24.2210
_cell_measurement_theta_min      2.9560
_cell_volume                     299.2(2)
_computing_cell_refinement       'CrysAlisPro 1.171.38.41 (Rigaku OD, 2015)'
_computing_data_collection       'CrysAlisPro 1.171.38.41 (Rigaku OD, 2015)'
_computing_data_reduction        'CrysAlisPro 1.171.38.41 (Rigaku OD, 2015)'
_computing_molecular_graphics    'Olex2 (Dolomanov et al., 2009)'
_computing_publication_material  'Olex2 (Dolomanov et al., 2009)'
_computing_structure_refinement  'ShelXL (Sheldrick, 2015)'
_computing_structure_solution    'ShelXT (Sheldrick, 2015)'
_diffrn_ambient_environment      N~2~
_diffrn_ambient_temperature      99.99(14)
_diffrn_detector                 'CCD plate'
_diffrn_detector_area_resol_mean 10.3590
_diffrn_detector_type            Atlas
_diffrn_measured_fraction_theta_full 1.000
_diffrn_measured_fraction_theta_max 1.000
_diffrn_measurement_details
;
List of Runs (angles in degrees, time in seconds):

  # Type    Start    End  Width  t~exp~   \w     \q     \k     \f   Frames
--------------------------------------------------------------------------
  1  \w    -25.00 119.00   1.00   60.00    --   18.69  77.00 150.00  144
  2  \w    -63.00  80.00   1.00   60.00    --  -19.78  77.00 -90.00  143
  3  \w    -63.00  80.00   1.00   60.00    --  -19.78  77.00  30.00  143
  4  \w    -28.00  83.00   1.00   60.00    --   18.69  38.00  30.00  111
;
_diffrn_measurement_device       'four-circle diffractometer'
_diffrn_measurement_device_type  'SuperNova, Single source at offset, Atlas'
_diffrn_measurement_method       '\w scans'
_diffrn_orient_matrix_type
'CrysAlisPro convention (1999,Acta A55,543-557)'
_diffrn_orient_matrix_UB_11      0.0689780000
_diffrn_orient_matrix_UB_12      0.1698775000
_diffrn_orient_matrix_UB_13      0.0179270000
_diffrn_orient_matrix_UB_21      0.1870307000
_diffrn_orient_matrix_UB_22      0.0366839000
_diffrn_orient_matrix_UB_23      -0.0041861000
_diffrn_orient_matrix_UB_31      0.0140752000
_diffrn_orient_matrix_UB_32      0.0982697000
_diffrn_orient_matrix_UB_33      -0.0292080000
_diffrn_radiation_monochromator  mirror
_diffrn_radiation_probe          x-ray
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.1405
_diffrn_reflns_av_unetI/netI     0.0593
_diffrn_reflns_Laue_measured_fraction_full 1.000
_diffrn_reflns_Laue_measured_fraction_max 1.000
_diffrn_reflns_limit_h_max       4
_diffrn_reflns_limit_h_min       -4
_diffrn_reflns_limit_k_max       4
_diffrn_reflns_limit_k_min       -4
_diffrn_reflns_limit_l_max       22
_diffrn_reflns_limit_l_min       -22
_diffrn_reflns_number            785
_diffrn_reflns_point_group_measured_fraction_full 1.000
_diffrn_reflns_point_group_measured_fraction_max 1.000
_diffrn_reflns_theta_full        23.183
_diffrn_reflns_theta_max         23.183
_diffrn_reflns_theta_min         2.976
_diffrn_source                   'micro-focus sealed X-ray tube'
_diffrn_source_type              'SuperNova (Mo) X-ray Source'
_exptl_absorpt_coefficient_mu    37.884
_exptl_absorpt_correction_T_max  1.00000
_exptl_absorpt_correction_T_min  0.31574
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details
;
CrysAlisPro 1.171.38.41 (Rigaku Oxford Diffraction, 2015)
Empirical absorption correction using spherical harmonics,
 implemented in SCALE3 ABSPACK scaling algorithm.
;
_exptl_crystal_colour            'metallic grayish gray'
_exptl_crystal_colour_lustre     metallic
_exptl_crystal_colour_modifier   grayish
_exptl_crystal_colour_primary    gray
_exptl_crystal_density_diffrn    6.625
_exptl_crystal_description       plate
_exptl_crystal_F_000             533
_exptl_crystal_size_max          0.07
_exptl_crystal_size_mid          0.025
_exptl_crystal_size_min          0.015
_refine_diff_density_max         2.741
_refine_diff_density_min         -1.283
_refine_diff_density_rms         0.474
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.070
_refine_ls_hydrogen_treatment    undef
_refine_ls_matrix_type           full
_refine_ls_number_parameters     15
_refine_ls_number_reflns         72
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.070
_refine_ls_R_factor_all          0.0860
_refine_ls_R_factor_gt           0.0791
_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^)+(0.1541P)^2^] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1837
_refine_ls_wR_factor_ref         0.1916
_reflns_Friedel_coverage         0.000
_reflns_number_gt                63
_reflns_number_total             72
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            lc5071.cif
_cod_data_source_block           Cu2-xSe_bulk_100K
_cod_original_cell_volume        299.2(3)
_cod_original_sg_symbol_H-M      'R -3 m'
_cod_database_code               1556755
_chemical_oxdiff_formula         Cu2Se
_reflns_odcompleteness_completeness 100.00
_reflns_odcompleteness_iscentric 1
_reflns_odcompleteness_theta     23.21
_olex2_refinement_description
;
1. Uiso/Uaniso restraints and constraints
Uanis(Se) = Uanis(Cu1B) = Uanis(Cu1A)
;