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_1556750
_publ_section_title
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 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(Cu5.83 Se3)'
_chemical_formula_sum            'Cu1.95 Se'
_chemical_formula_weight         202.86
_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'
_audit_creation_date             2017-01-24
_audit_creation_method
;
Olex2 1.2
(compiled 2017.01.04 svn.r3372 for OlexSys, GUI svn.r5292)
;
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                120
_cell_formula_units_Z            6
_cell_length_a                   4.1323(10)
_cell_length_b                   4.1323(10)
_cell_length_c                   20.358(9)
_cell_measurement_reflns_used    246
_cell_measurement_temperature    364.97(13)
_cell_measurement_theta_max      27.0510
_cell_measurement_theta_min      2.9530
_cell_volume                     301.06(17)
_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_temperature      364.97(13)
_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    -28.00 109.00   1.00   70.00    --   18.69  38.00 -60.00  137
  2  \w    -61.00  72.00   1.00   70.00    --  -19.62  57.00-150.00  133
  3  \w    -82.00  62.00   1.00   70.00    --   18.69 -77.00 -30.00  144
  4  \w     34.00  39.00   1.00   70.00    --   18.69-178.00-180.00    5
;
_diffrn_measurement_device       'four-circle diffractometer'
_diffrn_measurement_device_type  'SuperNova, Single source at offset, Atlas'
_diffrn_measurement_method       '\w scans'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0531
_diffrn_reflns_av_unetI/netI     0.0263
_diffrn_reflns_Laue_measured_fraction_full 1.000
_diffrn_reflns_Laue_measured_fraction_max 1.000
_diffrn_reflns_limit_h_max       5
_diffrn_reflns_limit_h_min       -4
_diffrn_reflns_limit_k_max       5
_diffrn_reflns_limit_k_min       -5
_diffrn_reflns_limit_l_max       24
_diffrn_reflns_limit_l_min       -24
_diffrn_reflns_number            772
_diffrn_reflns_point_group_measured_fraction_full 1.000
_diffrn_reflns_point_group_measured_fraction_max 1.000
_diffrn_reflns_theta_full        25.242
_diffrn_reflns_theta_max         26.203
_diffrn_reflns_theta_min         3.002
_exptl_absorpt_coefficient_mu    38.287
_exptl_absorpt_correction_T_max  1.00000
_exptl_absorpt_correction_T_min  0.20055
_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    6.714
_exptl_crystal_description       irregular
_exptl_crystal_F_000             543
_exptl_crystal_size_max          0.0908
_exptl_crystal_size_mid          0.0493
_exptl_crystal_size_min          0.0167
_refine_diff_density_max         2.233
_refine_diff_density_min         -2.676
_refine_diff_density_rms         0.566
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.389
_refine_ls_hydrogen_treatment    undef
_refine_ls_matrix_type           full
_refine_ls_number_parameters     19
_refine_ls_number_reflns         102
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      1.384
_refine_ls_R_factor_all          0.1027
_refine_ls_R_factor_gt           0.1004
_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^)+(0.2000P)^2^] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.2758
_refine_ls_wR_factor_ref         0.2778
_reflns_Friedel_coverage         0.000
_reflns_number_gt                97
_reflns_number_total             102
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            lc5071.cif
_cod_data_source_block           Cu1p95Se_CVT1_365K
_cod_original_cell_volume        301.1(2)
_cod_original_sg_symbol_H-M      'R -3 m'
_cod_database_code               1556750
_shelx_shelxl_version_number     2014/7
_shelx_estimated_absorpt_t_max   0.567
_shelx_estimated_absorpt_t_min   0.129
_olex2_refinement_description
;
1. Others
 1*[Sof(Cu1A)]+1*[Sof(Cu1B)]+3*[Sof(Cu2)]=1.95 with esd of 0.01
 Fixed X: Se1(0.3333) Cu1B(0.6667) Cu1A(0.6667)
 Fixed Y: Se1(0.6667) Cu1B(0.3333) Cu1A(0.3333)
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