data_global _amcsd_formula_title 'Lu2Si2O7' loop_ _publ_author_name 'Fleet M E' 'Liu X' _journal_name_full 'American Mineralogist' _journal_volume 89 _journal_year 2004 _journal_page_first 396 _journal_page_last 404 _publ_section_title ; A new rare earth disilicate (REE2Si2O7: REE = Dy, Tm, Lu; type-L): Evidence for nonquenchable 10 GPa polymorph with silicon in fivefold trigonal bipyramidal coordination? ; _database_code_amcsd 0003424 _chemical_formula_sum 'Lu5.745 Si6 O21' _cell_length_a 6.5240 _cell_length_b 6.5553 _cell_length_c 17.7909 _cell_angle_alpha 83.977 _cell_angle_beta 88.074 _cell_angle_gamma 87.846 _cell_volume 755.788 _exptl_crystal_density_diffrn 6.634 _symmetry_space_group_name_H-M 'P -1' loop_ _space_group_symop_operation_xyz 'x,y,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 Lu1 0.54296 0.03148 0.25839 0.96100 0.00970 Lu2 0.81377 0.53185 0.26105 0.97200 0.00930 Lu3 0.61557 0.34637 0.09551 0.96700 0.00890 Lu4 0.12070 0.64583 0.09097 0.90600 0.00950 Lu5 0.43223 0.62021 0.41313 0.97000 0.01580 Lu6 0.13704 0.11235 0.39622 0.96900 0.02060 Si1 0.65510 0.13970 0.41840 1.00000 0.01000 Si2 0.63110 0.82320 0.08190 1.00000 0.00880 Si3 0.12220 0.18100 0.06140 1.00000 0.01010 Si4 0.33850 0.51090 0.25920 1.00000 0.00930 Si5 0.00360 0.04120 0.21340 1.00000 0.00900 Si6A 0.96040 0.60240 0.44460 0.50000 0.00900 Si6B 0.90790 0.73300 0.44400 0.50000 0.01000 O1 0.23170 0.07660 0.98950 1.00000 0.01200 O2 0.44870 0.69000 0.05200 1.00000 0.01500 O3 0.91930 0.30950 0.03210 1.00000 0.01000 O4 0.27120 0.34380 0.08760 1.00000 0.00800 O5 0.77660 0.64210 0.12440 1.00000 0.01100 O6 0.56200 0.00810 0.12920 1.00000 0.01300 O7 0.08910 0.98250 0.12570 1.00000 0.00800 O8 0.87080 0.25190 0.19130 1.00000 0.01200 O9 0.13720 0.58550 0.21290 1.00000 0.01100 O10 0.50450 0.37610 0.21470 1.00000 0.00800 O11 0.84740 0.87250 0.24960 1.00000 0.00700 O12 0.19510 0.06050 0.26600 1.00000 0.01300 O13 0.48430 0.69560 0.27960 1.00000 0.01300 O14 0.79140 0.22520 0.34500 1.00000 0.03000 O15 0.27850 0.39940 0.34050 1.00000 0.02100 O16 0.77470 0.61450 0.38560 1.00000 0.02300 O17 0.47910 0.99940 0.38630 1.00000 0.00900 O18 0.13180 0.77280 0.40890 1.00000 0.01600 O19 0.81580 0.99100 0.46750 1.00000 0.02200 O20 0.55020 0.31590 0.46670 1.00000 0.01000 O21 0.10950 0.37420 0.46840 1.00000 0.03600