data_global _amcsd_formula_title 'BaCu2Ge2O7' loop_ _publ_author_name 'Yamada T' 'Hiroi Z' 'Takano M' _journal_name_full 'Journal of Solid State Chemistry' _journal_volume 156 _journal_year 2001 _journal_page_first 101 _journal_page_last 109 _publ_section_title ; Spin-1/2 quantum antiferromagnetic chains with tunable superexchange interactions found in BaCu2(Si1-xGex)2O7 ; _database_code_amcsd 0018762 _chemical_compound_source 'Synthetic' _chemical_formula_sum 'Ba Cu2 Ge2 O7' _cell_length_a 7.04765 _cell_length_b 13.40700 _cell_length_c 7.02755 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 90 _cell_volume 664.018 _exptl_crystal_density_diffrn 5.218 _symmetry_space_group_name_H-M 'P n m a' loop_ _space_group_symop_operation_xyz 'x,y,z' 'x,1/2-y,z' '-x,1/2+y,-z' '1/2-x,1/2+y,1/2+z' '1/2+x,1/2-y,1/2-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_U_iso_or_equiv Ba -0.02100 0.25000 0.94850 0.00747 Cu 0.21720 0.00400 0.79800 0.00798 Ge -0.00770 0.13050 0.47100 0.00241 O1 0.10070 0.25000 0.48310 0.00101 O2 -0.18840 0.13640 0.63410 0.01254 O3 -0.05630 0.11430 0.23570 0.01191 O4 0.16960 0.04760 0.53650 0.00621