data_global _chemical_name_mineral 'Terbium' loop_ _publ_author_name 'Spedding F H' 'Daane A H' 'Herrmann K W' _journal_name_full 'Acta Crystallographica' _journal_volume 9 _journal_year 1956 _journal_page_first 559 _journal_page_last 563 _publ_section_title ; The crystal structures and lattice parameters of high-purity scandium, yttrium and the rare earth metals Note: sample 99.9% pure ; _database_code_amcsd 0009174 _chemical_compound_source 'Synthetic' _chemical_formula_sum 'Tb' _cell_length_a 3.6010 _cell_length_b 3.6010 _cell_length_c 5.6936 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 120 _cell_volume 63.939 _exptl_crystal_density_diffrn 8.255 _symmetry_space_group_name_H-M 'P 63/m m c' loop_ _space_group_symop_operation_xyz 'x,y,z' '-x,-x+y,1/2+z' 'x,x-y,1/2-z' '-x+y,-x,1/2-z' 'x-y,x,1/2+z' '-y,-x,z' 'y,x,-z' 'y,-x+y,-z' '-y,x-y,z' 'x-y,-y,1/2+z' '-x+y,y,1/2-z' 'x,y,1/2-z' '-x,-y,1/2+z' 'x,x-y,z' '-x,-x+y,-z' 'x-y,x,-z' '-x+y,-x,z' 'y,x,1/2+z' '-y,-x,1/2-z' '-y,x-y,1/2-z' 'y,-x+y,1/2+z' '-x+y,y,z' 'x-y,-y,-z' '-x,-y,-z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z Tb 0.33333 0.66667 0.25000