Structural evolution of Na0.5K0.5NbO3 at high temperatures
Ishizawa, Nobuo; Wang, Jun; Sakakura, Terutoshi; Inagaki, Yumi; Kakimoto, Ken-ichi; Journal of Solid State Chemistry 183 (2010) 2731–2738; doi:10.1016/j.jssc.2010.09.018

data_1563470
_publ_section_title
;
 Structural evolution of Na0.5K0.5NbO3 at high temperatures
;
_journal_issue                   11
_journal_name_full               'Journal of Solid State Chemistry'
_journal_page_first              2731
_journal_page_last               2738
_journal_paper_doi               10.1016/j.jssc.2010.09.018
_journal_volume                  183
_journal_year                    2010
_chemical_formula_sum            'K0.25 Na0.25 Nb0.5 O1.5'
_chemical_formula_weight         85.98
_space_group_IT_number           99
_space_group_name_Hall           'P 4 -2'
_space_group_name_H-M_alt        'P 4 m m'
_symmetry_cell_setting           tetragonal
_symmetry_space_group_name_H-M   'P 4 m m'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                90.00
_cell_angle_beta                 90.00
_cell_angle_gamma                90.00
_cell_formula_units_Z            2
_cell_length_a                   3.9845(3)
_cell_length_b                   3.9845(3)
_cell_length_c                   4.01312(17)
_cell_measurement_temperature    642
_cell_volume                     63.713(7)
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 2008)'
_diffrn_ambient_temperature      642
_diffrn_measured_fraction_theta_full 0.967
_diffrn_measured_fraction_theta_max 0.967
_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  0.0204
_diffrn_reflns_av_sigmaI/netI    0.0184
_diffrn_reflns_limit_h_max       6
_diffrn_reflns_limit_h_min       -6
_diffrn_reflns_limit_k_max       7
_diffrn_reflns_limit_k_min       -7
_diffrn_reflns_limit_l_max       7
_diffrn_reflns_limit_l_min       -5
_diffrn_reflns_number            630
_diffrn_reflns_theta_full        40.03
_diffrn_reflns_theta_max         40.03
_diffrn_reflns_theta_min         5.08
_exptl_absorpt_coefficient_mu    5.353
_exptl_crystal_density_diffrn    4.482
_exptl_crystal_density_method    'not measured'
_exptl_crystal_F_000             80
_refine_diff_density_max         0.879
_refine_diff_density_min         -0.945
_refine_diff_density_rms         0.201
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   0.3(3)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.272
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     15
_refine_ls_number_reflns         226
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.272
_refine_ls_R_factor_all          0.0175
_refine_ls_R_factor_gt           0.0175
_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^)+(0.0266P)^2^+0.0117P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0458
_refine_ls_wR_factor_ref         0.0458
_reflns_number_gt                226
_reflns_number_total             226
_reflns_threshold_expression     >2\s(I)
_cod_data_source_file            100912_NKN_all.cif
_cod_data_source_block           i1_642K
_cod_original_cell_volume        63.714(7)
_cod_original_formula_sum        'K0.25 Na0.25 Nb0.50 O1.50'
_cod_database_code               1563470