data_global _amcsd_formula_title 'Ca2Ta2O7' loop_ _publ_author_name 'Grey I E' 'Mumme W G' 'Ness T J' 'Roth R S' 'Smith K L' _journal_name_full 'Journal of Solid State Chemistry' _journal_volume 174 _journal_year 2003 _journal_page_first 285 _journal_page_last 295 _publ_section_title ; Structural relations between weberite and zirconolite polytypes - refinements of doped 3T and 4M Ca2Ta2O7 and 3T CaZrTi2O7 Sample: T = 295 K, 4M weberite-type structure ; _database_code_amcsd 0014036 _chemical_formula_sum 'Ca7.676 Ta7.705 Nd.324 Zr.295 O28' _cell_length_a 12.761 _cell_length_b 7.358 _cell_length_c 24.565 _cell_angle_alpha 90 _cell_angle_beta 100.17 _cell_angle_gamma 90 _cell_volume 2270.302 _exptl_crystal_density_diffrn 6.505 _symmetry_space_group_name_H-M 'C 1 2 1' loop_ _space_group_symop_operation_xyz 'x,y,z' '1/2+x,1/2+y,z' '-x,y,-z' '1/2-x,1/2+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 Ca1 0.00000 0.00000 0.00000 1.00000 0.00270 Ta1 0.00000 0.48300 0.00000 1.00000 0.00230 Ca11 0.25650 0.26700 0.00670 0.95800 0.00600 NdCa11 0.25650 0.26700 0.00670 0.04200 0.00600 Ta2 0.12610 0.75300 0.12174 0.94600 0.00380 ZrTa2 0.12610 0.75300 0.12174 0.05400 0.00380 Ca2 0.12930 0.26900 0.12870 1.00000 0.02100 Ta21 0.37760 0.00700 0.12772 0.97400 0.00500 ZrTa21 0.37760 0.00700 0.12772 0.02600 0.00500 Ta22 0.38010 0.51000 0.12553 0.97600 0.00480 ZrTa22 0.38010 0.51000 0.12553 0.02400 0.00480 Ca3 0.25850 0.50710 0.24720 0.91800 0.00600 NdCa3 0.25850 0.50710 0.24720 0.08200 0.00600 Ta3 0.23950 0.01700 0.24980 1.00000 0.00640 Ca31 0.00970 0.25500 0.25490 1.00000 0.00210 Ca32 0.00840 0.74500 0.25040 1.00000 0.01500 Ta4 0.12830 0.50500 0.37414 0.95800 0.00460 ZrTa4 0.12830 0.50500 0.37414 0.04200 0.00460 Ca4 0.12780 0.00500 0.38010 0.87600 0.00860 NdCa4 0.12780 0.00500 0.38010 0.12400 0.00860 Ta41 0.37900 0.25600 0.37435 1.00000 0.00440 Ta42 0.37700 0.75400 0.37134 0.85100 0.00440 ZrTa42 0.37700 0.75400 0.37134 0.14900 0.00440 Ca5 0.00000 0.51200 0.50000 1.00000 0.02400 Ta5 0.00000 0.01100 0.50000 1.00000 0.00340 Ca51 0.24830 0.25800 0.49850 0.92400 0.00800 NdCa51 0.24830 0.25800 0.49850 0.07600 0.00800 O1 0.64000 0.99600 0.45660 1.00000 0.01300 O2 0.41500 0.48400 0.20680 1.00000 0.00800 O3 0.39200 0.01000 0.04810 1.00000 0.01000 O4 0.13700 0.00800 0.46810 1.00000 0.01100 O5 0.36600 0.01600 0.20620 1.00000 0.00900 O6 0.12500 0.99600 0.28980 1.00000 0.01200 O7 0.73600 0.79800 0.38770 1.00000 0.01800 O8 0.17100 0.23500 0.21360 1.00000 0.01300 O9 0.33200 0.19600 0.29670 1.00000 0.01100 O10 0.08600 0.69600 0.04370 1.00000 0.01800 O11 0.43100 0.30400 0.45450 1.00000 0.00800 O12 0.59000 0.80100 0.03710 1.00000 0.00600 O13 0.52600 0.80100 0.35880 1.00000 0.01300 O14 0.85500 0.50100 0.39770 1.00000 0.01600 O15 0.73100 0.42700 0.10220 1.00000 0.01700 O16 0.82300 0.75700 0.11460 1.00000 0.01300 O17 0.82700 0.30700 0.29150 1.00000 0.00800 O18 0.73100 0.05800 0.13690 1.00000 0.00800 O19 0.93400 0.25800 0.13740 1.00000 0.01200 O20 0.73400 0.20600 0.38790 1.00000 0.01300 O21 0.43500 0.70500 0.45100 1.00000 0.01900 O22 0.89800 0.00200 0.34970 1.00000 0.01600 O23 0.67200 0.32100 0.20240 1.00000 0.00800 O24 0.12100 0.50400 0.29310 1.00000 0.01000 O25 0.83800 0.03300 0.04370 1.00000 0.01500 O26 0.52500 0.09500 0.14910 1.00000 0.01200 O27 0.52500 0.20700 0.36280 1.00000 0.01300 O28 0.52400 0.45800 0.11110 1.00000 0.01300