K~2~NbAlO~2~[(As,Nb)O~4~]~2~, isostructural with KTiOPO~4~
Takeshi Nakagawa; Takeo Matsumoto; Valery I. Chani; Tsuguo Fukuda; Acta Crystallographica Section C 55 (1999) 1391–1393; doi:10.1107/S0108270199005144

data_2008940
_publ_section_title
;
 K~2~NbAlO~2~[(As,Nb)O~4~]~2~, isostructural with KTiOPO~4~
;
_journal_issue                   9
_journal_name_full               'Acta Crystallographica Section C'
_journal_page_first              1391
_journal_page_last               1393
_journal_paper_doi               10.1107/S0108270199005144
_journal_volume                  55
_journal_year                    1999
_chemical_formula_analytical     'Al0.99 As1.63 K1.97 Nb1.38 O10'
_chemical_formula_moiety         'K2 Nb Al O2 [(As0.8 Nb0.2) O4]2'
_chemical_formula_sum            'Al As1.6 K2 Nb1.4 O10'
_chemical_formula_weight         515.12
_chemical_name_systematic
;
potassium niobium alminium arsenate
;
_space_group_IT_number           33
_symmetry_cell_setting           orthorhombic
_symmetry_space_group_name_Hall  'P -2ac -2n'
_symmetry_space_group_name_H-M   'P n 21 a'
_cell_angle_alpha                90.00
_cell_angle_beta                 90.00
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   13.0060(10)
_cell_length_b                   10.6480(10)
_cell_length_c                   6.6190(10)
_cell_measurement_reflns_used    80
_cell_measurement_temperature    293(2)
_cell_measurement_theta_max      26
_cell_measurement_theta_min      10
_cell_volume                     916.65(18)
_computing_cell_refinement       'MSC/AFC Diffractometer Control Software'
_computing_data_collection
;
MSC/AFC Diffractometer Control Software
(Molecular Structure Corporation, 1993)
;
_computing_structure_refinement
'modified from the 1977 ORXFLS4 version of ORFLS (Busing et al., 1962)'
_diffrn_ambient_temperature      296.2
_diffrn_measurement_device       AFC7
_diffrn_measurement_method       \w-2\q
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'rotating Mo anode'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71069
_diffrn_reflns_av_R_equivalents  0.013
_diffrn_reflns_limit_h_max       18
_diffrn_reflns_limit_h_min       -18
_diffrn_reflns_limit_k_max       14
_diffrn_reflns_limit_k_min       -14
_diffrn_reflns_limit_l_max       9
_diffrn_reflns_limit_l_min       -10
_diffrn_reflns_number            8491
_diffrn_reflns_theta_max         34.96
_diffrn_reflns_theta_min         3.13
_diffrn_standards_decay_%        0.00
_diffrn_standards_interval_count 200
_diffrn_standards_number         3
_exptl_absorpt_coefficient_mu    8.57
_exptl_absorpt_correction_T_max  0.353
_exptl_absorpt_correction_T_min  0.269
_exptl_absorpt_correction_type   sphere
_exptl_absorpt_process_details
;
(modified PTPHI program in PW1100 software)
;
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    3.733
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       Sphere
_exptl_crystal_F_000             963
_exptl_crystal_size_rad          0.093(5)
_refine_diff_density_max         0.723
_refine_diff_density_min         -0.628
_refine_ls_extinction_coef       0.334(10)
_refine_ls_extinction_method     'Becker & Coppens (1974)'
_refine_ls_goodness_of_fit_all   1.991
_refine_ls_goodness_of_fit_ref   1.991
_refine_ls_hydrogen_treatment    none
_refine_ls_matrix_type           full
_refine_ls_number_constraints    42
_refine_ls_number_parameters     147
_refine_ls_number_reflns         2365
_refine_ls_number_restraints     0
_refine_ls_R_factor_gt           0.023
_refine_ls_shift/esd_mean        0.000
_refine_ls_shift/su_max          <0.001
_refine_ls_structure_factor_coef F
_refine_ls_weighting_details     'w = 1/[\s^2^(F~o~)]'
_refine_ls_weighting_scheme      sigma
_refine_ls_wR_factor_ref         0.034
_reflns_number_gt                2365
_reflns_number_total             2598
_reflns_observed_criterion       F>3\s(F)
_cod_data_source_file            oh1112.cif
_cod_data_source_block           KNAA
_cod_original_cell_volume        916.7(3)
_cod_original_formula_sum        'Al1.0 As1.6 K2 Nb1.4 O10'
_cod_database_code               2008940