Synthesis, structure, and polymorphism of A3LnSi2O7 (A=Na, K; Ln=Sm, Ho, Yb)
Latshaw, Allison M.; Yeon, Jeongho; Smith, Mark D.; zur Loye, Hans-Conrad; Journal of Solid State Chemistry 235 (2016) 100–106; doi:10.1016/j.jssc.2015.12.013

data_1561597
_publ_section_title
;
 Synthesis, structure, and polymorphism of A3LnSi2O7 (A=Na, K; Ln=Sm, Ho,
 Yb)
;
_journal_name_full               'Journal of Solid State Chemistry'
_journal_page_first              100
_journal_page_last               106
_journal_paper_doi               10.1016/j.jssc.2015.12.013
_journal_volume                  235
_journal_year                    2016
_chemical_formula_moiety         'Na3 O7 Si2 Yb'
_chemical_formula_sum            'Na3 O7 Si2 Yb'
_chemical_formula_weight         410.19
_space_group_crystal_system      trigonal
_space_group_IT_number           159
_space_group_name_Hall           'P 3 -2c'
_space_group_name_H-M_alt        'P 3 1 c'
_atom_sites_solution_hydrogens   .
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                120
_cell_formula_units_Z            18
_cell_length_a                   16.2081(2)
_cell_length_b                   16.2081(2)
_cell_length_c                   13.7077(4)
_cell_measurement_reflns_used    8934
_cell_measurement_temperature    296(2)
_cell_measurement_theta_max      35.270
_cell_measurement_theta_min      2.972
_cell_volume                     3118.60(11)
_computing_cell_refinement       'SAINT-Plus Version 6.45 (Bruker, 2001)'
_computing_data_collection       'SMART Version 5.631 (Bruker, 2001)'
_computing_data_reduction        'SAINT-Plus Version 6.45 (Bruker, 2001)'
_computing_molecular_graphics    various
_computing_publication_material  various
_computing_structure_refinement  'SHELXL-2014 (Sheldrick, 2014)'
_computing_structure_solution    'SHELXS97 (Sheldrick, 2008)'
_diffrn_ambient_temperature      296(2)
_diffrn_measured_fraction_theta_full 1.000
_diffrn_measured_fraction_theta_max 1.000
_diffrn_measurement_device_type  'Bruker SMART APEX CCD diffractometer'
_diffrn_measurement_method       'omega and phi scans'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0476
_diffrn_reflns_av_unetI/netI     0.0276
_diffrn_reflns_Laue_measured_fraction_full 1.000
_diffrn_reflns_Laue_measured_fraction_max 1.000
_diffrn_reflns_limit_h_max       26
_diffrn_reflns_limit_h_min       -26
_diffrn_reflns_limit_k_max       25
_diffrn_reflns_limit_k_min       -26
_diffrn_reflns_limit_l_max       22
_diffrn_reflns_limit_l_min       -22
_diffrn_reflns_number            86609
_diffrn_reflns_point_group_measured_fraction_full 1.000
_diffrn_reflns_point_group_measured_fraction_max 1.000
_diffrn_reflns_theta_full        25.242
_diffrn_reflns_theta_max         35.270
_diffrn_reflns_theta_min         1.451
_diffrn_source                   'sealed tube'
_exptl_absorpt_coefficient_mu    14.023
_exptl_absorpt_correction_T_max  1.0000
_exptl_absorpt_correction_T_min  0.4973
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   'SADABS Version 2.05 (Bruker, 2001)'
_exptl_crystal_colour            colorless
_exptl_crystal_density_diffrn    3.931
_exptl_crystal_description       'hexagonal plate'
_exptl_crystal_F_000             3366
_exptl_crystal_size_max          0.200
_exptl_crystal_size_mid          0.160
_exptl_crystal_size_min          0.050
_refine_diff_density_max         1.537
_refine_diff_density_min         -2.156
_refine_diff_density_rms         0.222
_refine_ls_abs_structure_details
; 
 Refined as an inversion twin. 
;
_refine_ls_extinction_coef       0.000307(17)
_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   1.069
_refine_ls_hydrogen_treatment    undef
_refine_ls_matrix_type           full
_refine_ls_number_parameters     356
_refine_ls_number_reflns         9324
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      1.068
_refine_ls_R_factor_all          0.0256
_refine_ls_R_factor_gt           0.0241
_refine_ls_shift/su_max          0.001
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w=1/[\s^2^(Fo^2^)+(0.0216P)^2^+3.6719P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0530
_refine_ls_wR_factor_ref         0.0536
_reflns_Friedel_coverage         0.995
_reflns_Friedel_fraction_full    1.000
_reflns_Friedel_fraction_max     1.000
_reflns_number_gt                9067
_reflns_number_total             9324
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            mmc4.cif
_cod_data_source_block           Na3YbSi2O7
_cod_original_cell_volume        3118.60(12)
_cod_database_code               1561597
_shelx_estimated_absorpt_t_min   0.166
_shelx_estimated_absorpt_t_max   0.541