The crystal structures of Hf3±δNb4±δAs3 and Hf7.2Nb3.8As4: Members of a homologous series combining W-type, Mg-type and AlB2-type building blocks
Chumak, Igor; Warczok, Piotr; Richter, Klaus W.; Journal of Solid State Chemistry 183 (2010) 557–564; doi:10.1016/j.jssc.2009.12.028

data_1563689
_publ_section_title
;
 The crystal structures of Hf3+-\dNb4+-\dAs3 and Hf7.2Nb3.8As4: Members of
 a homologous series combining W-type, Mg-type and AlB2-type building
 blocks
;
_journal_issue                   3
_journal_name_full               'Journal of Solid State Chemistry'
_journal_page_first              557
_journal_page_last               564
_journal_paper_doi               10.1016/j.jssc.2009.12.028
_journal_volume                  183
_journal_year                    2010
_chemical_formula_sum            'As4 Hf7.2 Nb3.8'
_chemical_formula_weight         1937.9
_space_group_IT_number           71
_space_group_name_Hall           '-I 2 2'
_space_group_name_H-M_alt        'I m m m'
_symmetry_cell_setting           orthorhombic
_symmetry_space_group_name_H-M   'I m m m'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_cell_angle_alpha                90.00
_cell_angle_beta                 90.00
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   3.5825(7)
_cell_length_b                   9.6162(19)
_cell_length_c                   16.103(3)
_cell_measurement_temperature    293(2)
_cell_volume                     554.75(19)
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      293(2)
_diffrn_measured_fraction_theta_full 0.992
_diffrn_measured_fraction_theta_max 0.992
_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  0.0339
_diffrn_reflns_av_sigmaI/netI    0.0256
_diffrn_reflns_limit_h_max       2
_diffrn_reflns_limit_h_min       -5
_diffrn_reflns_limit_k_max       13
_diffrn_reflns_limit_k_min       -13
_diffrn_reflns_limit_l_max       22
_diffrn_reflns_limit_l_min       -22
_diffrn_reflns_number            2580
_diffrn_reflns_theta_full        30.10
_diffrn_reflns_theta_max         30.10
_diffrn_reflns_theta_min         4.24
_exptl_absorpt_coefficient_mu    84.021
_exptl_crystal_density_diffrn    11.691
_exptl_crystal_density_method    'not measured'
_exptl_crystal_F_000             1623
_refine_diff_density_max         3.734
_refine_diff_density_min         -3.281
_refine_diff_density_rms         0.712
_refine_ls_extinction_coef       0.00043(6)
_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   1.188
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     33
_refine_ls_number_reflns         508
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.188
_refine_ls_R_factor_all          0.0339
_refine_ls_R_factor_gt           0.0260
_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^)+(0.0304P)^2^+9.4869P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0599
_refine_ls_wR_factor_ref         0.0628
_reflns_number_gt                410
_reflns_number_total             508
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            JSSC-2010-183-557.cif
_cod_data_source_block           71hf
_cod_original_cell_volume        554.74(19)
_cod_original_sg_symbol_H-M      Immm
_cod_database_code               1563689