data_global _chemical_name_mineral 'Effenbergerite' loop_ _publ_author_name 'Knight K S' 'Henderson C M B' _journal_name_full 'European Journal of Mineralogy' _journal_volume 19 _journal_year 2007 _journal_page_first 189 _journal_page_last 200 _publ_section_title ; Structural basis for the anomalous low-temperature thermal expansion behavior of the gillespite-structured phase Ba0.5Sr0.5CuSi4O10 Sample: T = 50 K ; _database_code_amcsd 0007201 _chemical_formula_sum '(Ba.5 Sr.5) Cu Si4 O10' _cell_length_a 7.39601 _cell_length_b 7.39601 _cell_length_c 15.8469 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 90 _cell_volume 866.841 _exptl_crystal_density_diffrn 3.436 _symmetry_space_group_name_H-M 'P 4/n c c' loop_ _space_group_symop_operation_xyz 'x,y,z' '1/2-y,1/2-x,1/2+z' '1/2+y,1/2+x,1/2-z' '1/2+y,-x,-z' '1/2-y,x,z' 'x,1/2-y,1/2+z' '-x,1/2+y,1/2-z' '1/2+x,1/2+y,-z' '1/2-x,1/2-y,z' 'y,x,1/2+z' '-y,-x,1/2-z' '-y,1/2+x,-z' 'y,1/2-x,z' '1/2-x,y,1/2+z' '1/2+x,-y,1/2-z' '-x,-y,-z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_occupancy _atom_site_U_iso_or_equiv Ba 0.25000 0.75000 0.00000 0.50000 0.02810 Sr 0.25000 0.75000 0.00000 0.50000 0.02810 Cu 0.25000 0.25000 0.09149 1.00000 0.04980 Si 0.51230 0.93350 0.15179 1.00000 0.02630 O1 0.45430 0.98420 0.24590 0.50000 0.06060 O2 0.71780 -0.00010 0.13316 1.00000 0.05740 O3 0.37370 0.02340 0.08818 1.00000 0.06760