data_global _amcsd_formula_title 'Ba3Ta6Si4O26' loop_ _publ_author_name 'Choisnet J' 'Nguyen N' 'Groult D' 'Raveau B' _journal_name_full 'Materials Research Bulletin' _journal_volume 11 _journal_year 1976 _journal_page_first 887 _journal_page_last 894 _publ_section_title ; De nouveaux oxydes a reseau forme d'octahedres NbO6 (TaO6) et de groupes Si2O7: Les phases A3Ta6Si4O26 (A = Ba,Sr) et K6M6Si4O26 (M = Nb,Ta) ; _database_code_amcsd 0014243 _chemical_formula_sum 'Ba3 Ta6 Si4 O26' _cell_length_a 9.001 _cell_length_b 9.001 _cell_length_c 7.734 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 120 _cell_volume 542.646 _exptl_crystal_density_diffrn 6.200 _symmetry_space_group_name_H-M 'P -6 2 m' loop_ _space_group_symop_operation_xyz 'x,y,z' '-x,-x+y,z' '-x+y,-x,-z' 'y,x,-z' '-y,x-y,z' 'x-y,-y,z' 'x,y,-z' '-x,-x+y,-z' '-x+y,-x,z' 'y,x,z' '-y,x-y,-z' 'x-y,-y,-z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_U_iso_or_equiv Ba 0.59500 0.00000 0.50000 0.02710 Ta 0.24200 0.00000 0.23900 0.01013 Si 0.33333 0.66667 0.20700 0.01102 O1 0.33333 0.66667 0.00000 0.01963 O2 0.31400 0.00000 0.00000 0.01608 O3 0.80900 0.00000 0.24200 0.01963 O4 0.50000 0.17400 0.27900 0.01773 O5 0.20800 0.00000 0.50000 0.02052