The Reversible α →β Phase Transition of Cu2As2O7
Weil, Matthias; Lengauer, Christian; Füglein, Ekkehard; Baran, Enrique J.; Crystal Growth & Design 4 (2004) 1229–; doi:10.1021/cg049782o

data_4505377
_publ_section_title
;
 The Reversible \a \\rightarrow \b Phase Transition of Cu2As2O7
;
_journal_issue                   6
_journal_name_full               'Crystal Growth &amp; Design'
_journal_page_first              1229
_journal_paper_doi               10.1021/cg049782o
_journal_volume                  4
_journal_year                    2004
_chemical_formula_structural     'Cu2 (As2 O7)'
_chemical_formula_sum            'As2 Cu2 O7'
_chemical_formula_weight         388.92
_chemical_name_common            Copperpyroarsenate
_chemical_name_systematic
; 
Copper(II) diarsenate(V) 
;
_space_group_IT_number           15
_symmetry_cell_setting           monoclinic
_symmetry_space_group_name_Hall  '-C 2yc'
_symmetry_space_group_name_H-M   'C 1 2/c 1'
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                90.00
_cell_angle_beta                 111.03(2)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   7.237(3)
_cell_length_b                   8.2557(17)
_cell_length_c                   9.780(3)
_cell_measurement_reflns_used    25
_cell_measurement_temperature    293(2)
_cell_measurement_theta_max      16.04
_cell_measurement_theta_min      11.89
_cell_volume                     545.4(3)
_computing_cell_refinement       'CAD4 express'
_computing_data_collection       'CAD4 express (Nonius, 1991)'
_computing_data_reduction        'Helena (Spek, 2003)'
_computing_molecular_graphics    'Atoms for Windows V5.1 (Dowty, 2000)'
_computing_publication_material  SHELXL97
_computing_structure_refinement  'SHELXL97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS97 (Sheldrick, 1997)'
_diffrn_ambient_temperature      293(2)
_diffrn_measured_fraction_theta_full 0.999
_diffrn_measured_fraction_theta_max 0.999
_diffrn_measurement_device_type  'CAD4 (Nonius)'
_diffrn_measurement_method       \w/2\q
_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  0.0833
_diffrn_reflns_av_sigmaI/netI    0.0507
_diffrn_reflns_limit_h_max       11
_diffrn_reflns_limit_h_min       -11
_diffrn_reflns_limit_k_max       13
_diffrn_reflns_limit_k_min       -13
_diffrn_reflns_limit_l_max       15
_diffrn_reflns_limit_l_min       -15
_diffrn_reflns_number            4627
_diffrn_reflns_theta_full        34.96
_diffrn_reflns_theta_max         34.96
_diffrn_reflns_theta_min         3.90
_diffrn_standards_decay_%        0
_diffrn_standards_interval_time  120
_diffrn_standards_number         3
_exptl_absorpt_coefficient_mu    19.821
_exptl_absorpt_correction_T_max  0.0850
_exptl_absorpt_correction_T_min  0.0158
_exptl_absorpt_correction_type   numerical
_exptl_crystal_colour            olive
_exptl_crystal_density_diffrn    4.736
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       fragment
_exptl_crystal_F_000             720
_exptl_crystal_size_max          0.796
_exptl_crystal_size_mid          0.288
_exptl_crystal_size_min          0.252
_refine_diff_density_max         1.729
_refine_diff_density_min         -1.767
_refine_diff_density_rms         0.281
_refine_ls_extinction_coef       0.081(3)
_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   1.169
_refine_ls_matrix_type           full
_refine_ls_number_parameters     52
_refine_ls_number_reflns         1194
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.169
_refine_ls_R_factor_all          0.0287
_refine_ls_R_factor_gt           0.0278
_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^)+(0.0331P)^2^+1.3402P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0749
_refine_ls_wR_factor_ref         0.0755
_reflns_number_gt                1156
_reflns_number_total             1194
_reflns_threshold_expression     I>2\s(I)
_cod_data_source_file            cg049782osi20040706_123518.cif
_cod_data_source_block           cu2as2o7
_cod_original_sg_symbol_H-M      'C 2/c'
_cod_database_code               4505377