data_2002951 _journal_name_full 'Acta Crystallographica, Section B' _journal_year 1998 _journal_volume B54 _journal_page_first 399 _journal_page_last 416 _publ_section_title ; Centrosymmetric or Noncentrosymmetric? Case Study and Structural Redetermination of Sr~5~Nb~5~O~17~ ; loop_ _publ_author_name 'Abrahams, Sidney C.' 'Schmalle, Helmut W.' 'Williams, Tim' 'Reller, Armin' 'Lichtenberg, Frank' 'Widmer, Daniel' 'Bednorz, J. Georg' 'Spreiter, Rolf' 'Bosshard, Christian' 'G\"unter, Peter' _chemical_name_systematic ; strontium niobium oxide ; _chemical_formula_sum 'Nb5 O17 Sr5' _chemical_formula_weight 1174.65 _symmetry_cell_setting Orthorhombic _symmetry_space_group_name_H-M 'P n n m' _symmetry_space_group_name_Hall '-P 2 2n' loop_ _symmetry_equiv_pos_as_xyz 'x, y, z' '-x, -y, z' '-x+1/2, y+1/2, -z+1/2' 'x+1/2, -y+1/2, -z+1/2' '-x, -y, -z' 'x, y, -z' 'x-1/2, -y-1/2, z-1/2' '-x-1/2, y-1/2, z-1/2' _cell_length_a 32.456(5) _cell_length_b 5.674(2) _cell_length_c 3.995(2) _cell_angle_alpha 90.00 _cell_angle_beta 90.00 _cell_angle_gamma 90.00 _cell_volume 735.7(5) _cell_formula_units_Z 2 _cell_measurement_reflns_used 25 _cell_measurement_theta_min 5.6 _cell_measurement_theta_max 12.0 _cell_measurement_temperature 295(2) _exptl_crystal_description Platelike _exptl_crystal_colour Black _exptl_crystal_size_max .387 _exptl_crystal_size_mid .135 _exptl_crystal_size_min .035 _exptl_crystal_density_diffrn 5.303 _exptl_crystal_density_meas ? _exptl_crystal_density_method ? _exptl_crystal_F_000 1062 _exptl_absorpt_coefficient_mu 21.803 _exptl_absorpt_correction_type numerical _exptl_absorpt_correction_T_min .0665 _exptl_absorpt_correction_T_max .7868 _diffrn_ambient_temperature 295(2) _diffrn_radiation_type MoK\a _diffrn_radiation_wavelength .71073 _diffrn_radiation_source 'fine-focus sealed tube' _diffrn_radiation_monochromator graphite _diffrn_measurement_device 'Enraf-Nonius CAD-4 diffractometer' _diffrn_measurement_method '\w-2\q scans' _diffrn_reflns_number 17414 _diffrn_reflns_av_R_equivalents .0650 _diffrn_reflns_av_sigmaI/netI .0410 _diffrn_reflns_theta_min 1.25 _diffrn_reflns_theta_max 39.94 _diffrn_reflns_limit_h_min -58 _diffrn_reflns_limit_h_max 58 _diffrn_reflns_limit_k_min -10 _diffrn_reflns_limit_k_max 10 _diffrn_reflns_limit_l_min -7 _diffrn_reflns_limit_l_max 7 _diffrn_standards_number 3 _diffrn_standards_interval_count 400 _diffrn_standards_interval_time 180 _diffrn_standards_decay_% -1.7 _reflns_number_total 2515 _reflns_number_observed 1461 _reflns_observed_criterion >2sigma(I) _refine_ls_structure_factor_coef Fsqd _refine_ls_matrix_type full _refine_ls_R_factor_all .0611 _refine_ls_R_factor_obs .0221 _refine_ls_wR_factor_all .0655 _refine_ls_wR_factor_obs .0575 _refine_ls_goodness_of_fit_all .764 _refine_ls_goodness_of_fit_obs .925 _refine_ls_restrained_S_all .764 _refine_ls_restrained_S_obs .925 _refine_ls_number_reflns 2515 _refine_ls_number_parameters 86 _refine_ls_number_restraints 0 _refine_ls_weighting_scheme 'calc w=1/[\s^2^(Fo^2^)+(0.0217P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3' _refine_ls_shift/esd_mean .000 _refine_diff_density_max 4.632 _refine_diff_density_min -4.320 _refine_ls_extinction_method SHELXL _refine_ls_extinction_coef .00441(17) loop_ _atom_type_symbol _atom_type_description _atom_type_scat_dispersion_real _atom_type_scat_dispersion_imag _atom_type_scat_source 'O' 'O' .0106 .0060 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'Nb' 'Nb' -2.0727 .6215 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'Sr' 'Sr' -1.5307 3.2498 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_U_iso_or_equiv _atom_site_thermal_displace_type _atom_site_calc_flag _atom_site_refinement_flags _atom_site_occupancy _atom_site_disorder_group _atom_site_type_symbol Nb1 .5000 .5000 .5000 .00362(8) Uani d S 1 . Nb Nb2 .322645(11) .53337(5) .5000 .00526(6) Uani d S 1 . Nb Nb3 .409303(11) .00516(5) .5000 .00383(6) Uani d S 1 . Nb Sr1 .214545(16) .56286(7) .5000 .01512(10) Uani d S 1 . Sr Sr2 .5000 .0000 .0000 .00856(9) Uani d S 1 . Sr Sr3 .411315(13) .49960(6) .0000 .00819(7) Uani d S 1 . Sr O1 .53746(10) .2262(4) .5000 .0120(5) Uani d S 1 . O O2 .45215(9) .2687(4) .5000 .0087(5) Uani d S 1 . O O3 .5000 .5000 .0000 .0155(9) Uani d S 1 . O O4 .20898(10) .2970(5) .0000 .0137(6) Uani d S 1 . O O5 .12093(9) .2075(4) .0000 .0078(5) Uani d S 1 . O O6 .13278(10) .7229(5) .0000 .0183(7) Uani d S 1 . O O7 .27977(10) .3168(4) .5000 .0099(5) Uani d S 1 . O O8 .33088(10) .5046(6) .0000 .0172(6) Uani d S 1 . O O9 .41633(10) -.0090(5) .0000 .0144(6) Uani d S 1 . O loop_ _atom_site_aniso_label _atom_site_aniso_U_11 _atom_site_aniso_U_22 _atom_site_aniso_U_33 _atom_site_aniso_U_12 _atom_site_aniso_U_13 _atom_site_aniso_U_23 Nb1 .00400(17) .00388(14) .00298(17) -.00001(12) .000 .000 Nb2 .00526(13) .00588(10) .00464(12) -.00048(10) .000 .000 Nb3 .00428(12) .00380(10) .00341(12) -.00015(9) .000 .000 Sr1 .0246(2) .01510(16) .00568(15) .00863(15) .000 .000 Sr2 .0091(2) .00902(18) .0076(2) -.00100(15) .000 .000 Sr3 .00930(15) .00923(13) .00604(15) .00184(11) .000 .000 O1 .0053(12) .0084(10) .0222(15) .0021(9) .000 .000 O2 .0081(13) .0073(9) .0106(13) -.0030(9) .000 .000 O3 .014(2) .030(2) .0032(16) -.0056(17) .000 .000 O4 .0161(16) .0092(10) .0160(14) -.0056(10) .000 .000 O5 .0067(12) .0070(9) .0097(12) .0016(8) .000 .000 O6 .0085(14) .0104(10) .036(2) -.0050(10) .000 .000 O7 .0126(14) .0067(9) .0104(12) -.0042(9) .000 .000 O8 .0068(12) .0402(18) .0046(12) -.0039(13) .000 .000 O9 .0119(15) .0270(15) .0043(12) -.0096(12) .000 .000