data_global _amcsd_formula_title 'Dy2Si2O7' 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 0003422 _chemical_formula_sum 'Dy6 Si6 O21' _cell_length_a 6.5971 _cell_length_b 6.6504 _cell_length_c 18.0582 _cell_angle_alpha 83.791 _cell_angle_beta 88.653 _cell_angle_gamma 88.498 _cell_volume 787.185 _exptl_crystal_density_diffrn 6.242 _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 Dy1 0.54669 0.03160 0.25884 1.00000 0.00770 Dy2 0.81887 0.52945 0.26374 1.00000 0.00820 Dy3 0.61495 0.34691 0.09507 1.00000 0.00670 Dy4 0.12017 0.65444 0.08928 1.00000 0.00980 Dy5 0.42509 0.62047 0.41389 1.00000 0.01520 Dy6 0.13288 0.11258 0.39816 1.00000 0.01870 Si1 0.65170 0.13470 0.41890 1.00000 0.00660 Si2 0.63580 0.82300 0.08010 1.00000 0.00510 Si3 0.12320 0.18430 0.06260 1.00000 0.00690 Si4 0.33830 0.51080 0.25790 1.00000 0.00600 Si5 0.00520 0.04370 0.21380 1.00000 0.00590 Si6A 0.95520 0.60240 0.44690 0.50000 0.01200 Si6B 0.89990 0.73400 0.44360 0.50000 0.00900 O1 0.21800 0.08110 0.99090 1.00000 0.01200 O2 0.45580 0.69620 0.04750 1.00000 0.00900 O3 0.92140 0.30940 0.03560 1.00000 0.01200 O4 0.27270 0.34640 0.08640 1.00000 0.00800 O5 0.77570 0.64520 0.12440 1.00000 0.01100 O6 0.56550 0.00420 0.12640 1.00000 0.01000 O7 0.08640 0.99370 0.12640 1.00000 0.00600 O8 0.86850 0.24970 0.19380 1.00000 0.01100 O9 0.14470 0.58750 0.21030 1.00000 0.01000 O10 0.50230 0.37210 0.21590 1.00000 0.00800 O11 0.85180 0.87010 0.24720 1.00000 0.00800 O12 0.19650 0.06240 0.26550 1.00000 0.01100 O13 0.48650 0.68970 0.28080 1.00000 0.00800 O14 0.77990 0.22230 0.34510 1.00000 0.01300 O15 0.26320 0.40220 0.33830 1.00000 0.01900 O16 0.77050 0.61480 0.38670 1.00000 0.02700 O17 0.47090 0.99770 0.38710 1.00000 0.01000 O18 0.11820 0.77160 0.41180 1.00000 0.02100 O19 0.81520 0.99070 0.46730 1.00000 0.02600 O20 0.54890 0.30460 0.46680 1.00000 0.01200 O21 0.11840 0.37550 0.47260 1.00000 0.03100