data_Ca4Ta2O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.76
_cell_length_b   5.76
_cell_length_c   14.87
_cell_angle_alpha   89.9
_cell_angle_beta   89.8
_cell_angle_gamma   60.05
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Ca4Ta2O9
_chemical_formula_sum   'Ca8 Ta4 O18'
_cell_volume   427.79
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Ca  Ca0  1  0.05  0.01  0.08  1.0
  Ca  Ca1  1  0.03  1.0  0.44  1.0
  Ca  Ca2  1  0.0  0.0  0.0  1.0
  Ca  Ca3  1  0.92  0.66  0.76  1.0
  Ca  Ca4  1  0.96  0.66  0.46  1.0
  Ca  Ca5  1  0.73  0.33  0.41  1.0
  Ca  Ca6  1  0.77  0.33  0.11  1.0
  Ca  Ca7  1  0.64  0.98  0.8  1.0
  Ta  Ta8  1  0.86  0.67  0.24  1.0
  Ta  Ta9  1  0.89  0.66  0.22  1.0
  Ta  Ta10  1  0.8  0.33  0.66  1.0
  Ta  Ta11  1  0.83  0.32  0.63  1.0
  O  O12  1  0.33  0.9  0.69  1.0
  O  O13  1  0.86  0.26  0.97  1.0
  O  O14  1  0.83  0.34  0.34  1.0
  O  O15  1  0.2  0.27  0.94  1.0
  O  O16  1  0.21  0.22  0.32  1.0
  O  O17  1  0.45  0.21  0.67  1.0
  O  O18  1  0.87  0.88  0.66  1.0
  O  O19  1  0.2  0.54  0.61  1.0
  O  O20  1  0.06  0.52  0.91  1.0
  O  O21  1  0.63  0.47  0.96  1.0
  O  O22  1  0.49  0.45  0.26  1.0
  O  O23  1  0.82  0.11  0.21  1.0
  O  O24  1  0.24  0.78  0.2  1.0
  O  O25  1  0.48  0.77  0.55  1.0
  O  O26  1  0.49  0.72  0.93  1.0
  O  O27  1  0.86  0.65  0.54  1.0
  O  O28  1  0.83  0.73  0.91  1.0
  O  O29  1  0.36  0.09  0.19  1.0

data_Ca4Ta2O9
_symmetry_space_group_name_H-M   P1
_cell_length_a   5.76
_cell_length_b   5.76
_cell_length_c   14.87
_cell_angle_alpha   89.9
_cell_angle_beta   89.8
_cell_angle_gamma   60.05
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Ca4Ta2O9
_chemical_formula_sum   'Ca8 Ta4 O18'
_cell_volume   427.79
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Ca  Ca0  1  0.0  0.0  0.0  1.0
  Ca  Ca1  1  0.03  1.0  0.44  1.0
  Ca  Ca2  1  0.05  0.01  0.08  1.0
  Ca  Ca3  1  0.64  0.98  0.8  1.0
  Ca  Ca4  1  0.73  0.33  0.41  1.0
  Ca  Ca5  1  0.77  0.33  0.11  1.0
  Ca  Ca6  1  0.92  0.66  0.76  1.0
  Ca  Ca7  1  0.96  0.66  0.46  1.0
  Ta  Ta8  1  0.8  0.33  0.66  1.0
  Ta  Ta9  1  0.83  0.32  0.63  1.0
  Ta  Ta10  1  0.86  0.67  0.24  1.0
  Ta  Ta11  1  0.89  0.66  0.22  1.0
  O  O12  1  0.06  0.52  0.91  1.0
  O  O13  1  0.2  0.54  0.61  1.0
  O  O14  1  0.2  0.27  0.94  1.0
  O  O15  1  0.21  0.22  0.32  1.0
  O  O16  1  0.24  0.78  0.2  1.0
  O  O17  1  0.33  0.9  0.69  1.0
  O  O18  1  0.36  0.09  0.19  1.0
  O  O19  1  0.45  0.21  0.67  1.0
  O  O20  1  0.48  0.77  0.55  1.0
  O  O21  1  0.49  0.72  0.93  1.0
  O  O22  1  0.49  0.45  0.26  1.0
  O  O23  1  0.63  0.47  0.96  1.0
  O  O24  1  0.82  0.11  0.21  1.0
  O  O25  1  0.83  0.34  0.34  1.0
  O  O26  1  0.83  0.73  0.91  1.0
  O  O27  1  0.86  0.26  0.97  1.0
  O  O28  1  0.86  0.65  0.54  1.0
  O  O29  1  0.87  0.88  0.66  1.0

Ca Ca Ca Ca Ca Ca Ca Ca Ta Ta Ta Ta O O O O O O O O O O O O O O O O O O
Ca3(CaTa2)O9 crystallizes in the triclinic P1 space group. There are eight inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 5-coordinate geometry to one Ca(3), one Ca(7), one O(12), one O(13), one O(18), and one O(4) atom. The Ca(1)-Ca(3) bond length is 1.19 Å. The Ca(1)-Ca(7) bond length is 1.81 Å. The Ca(1)-O(12) bond length is 2.33 Å. The Ca(1)-O(13) bond length is 2.22 Å. The Ca(1)-O(18) bond length is 2.63 Å. The Ca(1)-O(4) bond length is 2.88 Å. In the second Ca site, Ca(2) is bonded in a 5-coordinate geometry to one Ca(5), one Ca(6), one O(14), one O(3), and one O(5) atom. The Ca(2)-Ca(5) bond length is 2.19 Å. The Ca(2)-Ca(6) bond length is 1.86 Å. The Ca(2)-O(14) bond length is 2.82 Å. The Ca(2)-O(3) bond length is 2.27 Å. The Ca(2)-O(5) bond length is 2.64 Å. In the third Ca site, Ca(3) is bonded in a single-bond geometry to one Ca(1), one O(15), one O(17), one O(2), one O(4), and one O(9) atom. The Ca(3)-O(15) bond length is 2.66 Å. The Ca(3)-O(17) bond length is 2.60 Å. The Ca(3)-O(2) bond length is 1.38 Å. The Ca(3)-O(4) bond length is 2.52 Å. The Ca(3)-O(9) bond length is 2.89 Å. In the fourth Ca site, Ca(4) is bonded in a distorted single-bond geometry to one O(17), one O(7), one O(8), and one O(9) atom. The Ca(4)-O(17) bond length is 2.23 Å. The Ca(4)-O(7) bond length is 1.87 Å. The Ca(4)-O(8) bond length is 2.56 Å. The Ca(4)-O(9) bond length is 2.43 Å. In the fifth Ca site, Ca(5) is bonded in a single-bond geometry to one Ca(2), one O(16), one O(5), and one O(8) atom. The Ca(5)-O(16) bond length is 1.29 Å. The Ca(5)-O(5) bond length is 2.98 Å. The Ca(5)-O(8) bond length is 2.56 Å. In the sixth Ca site, Ca(6) is bonded in a single-bond geometry to one Ca(2), one O(11), one O(14), and one O(3) atom. The Ca(6)-O(11) bond length is 2.56 Å. The Ca(6)-O(14) bond length is 2.98 Å. The Ca(6)-O(3) bond length is 1.29 Å. In the seventh Ca site, Ca(7) is bonded in a distorted single-bond geometry to one Ca(1), one O(10), one O(11), and one O(12) atom. The Ca(7)-O(10) bond length is 2.43 Å. The Ca(7)-O(11) bond length is 2.56 Å. The Ca(7)-O(12) bond length is 1.87 Å. In the eighth Ca site, Ca(8) is bonded in a 2-coordinate geometry to one O(1), one O(17), one O(4), and one O(6) atom. The Ca(8)-O(1) bond length is 2.63 Å. The Ca(8)-O(17) bond length is 2.09 Å. The Ca(8)-O(4) bond length is 3.14 Å. The Ca(8)-O(6) bond length is 2.22 Å. There are four inequivalent Ta sites. In the first Ta site, Ta(1) is bonded in a distorted single-bond geometry to one Ta(2), one O(11), and one O(5) atom. The Ta(1)-Ta(2) bond length is 0.42 Å. The Ta(1)-O(11) bond length is 2.98 Å. The Ta(1)-O(5) bond length is 2.64 Å. In the second Ta site, Ta(2) is bonded in a distorted single-bond geometry to one Ta(1) and one O(13) atom. The Ta(2)-O(13) bond length is 2.41 Å. In the third Ta site, Ta(3) is bonded in a distorted single-bond geometry to one Ta(4) and one O(6) atom. The Ta(3)-Ta(4) bond length is 0.42 Å. The Ta(3)-O(6) bond length is 2.41 Å. In the fourth Ta site, Ta(4) is bonded in a distorted single-bond geometry to one Ta(3), one O(14), and one O(8) atom. The Ta(4)-O(14) bond length is 2.64 Å. The Ta(4)-O(8) bond length is 2.98 Å. There are eighteen inequivalent O sites. In the first O site, O(1) is bonded in a 1-coordinate geometry to one Ca(8) atom. In the second O site, O(2) is bonded in a single-bond geometry to one Ca(3), one O(10), and one O(4) atom. The O(2)-O(10) bond length is 1.29 Å. The O(2)-O(4) bond length is 2.03 Å. In the third O site, O(3) is bonded in a single-bond geometry to one Ca(2), one Ca(6), one O(11), and one O(5) atom. The O(3)-O(11) bond length is 2.04 Å. The O(3)-O(5) bond length is 1.97 Å. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to one Ca(1), one Ca(3), one Ca(8), one O(2), and one O(9) atom. The O(4)-O(9) bond length is 1.33 Å. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Ca(2), one Ca(5), one Ta(1), and one O(3) atom. In the sixth O site, O(6) is bonded in a 2-coordinate geometry to one Ca(8), one Ta(3), and one O(8) atom. The O(6)-O(8) bond length is 1.91 Å. In the seventh O site, O(7) is bonded in a distorted single-bond geometry to one Ca(4) and one O(8) atom. The O(7)-O(8) bond length is 2.03 Å. In the eighth O site, O(8) is bonded in a 6-coordinate geometry to one Ca(4), one Ca(5), one Ta(4), one O(16), one O(6), and one O(7) atom. The O(8)-O(16) bond length is 2.04 Å. In the ninth O site, O(9) is bonded in a 4-coordinate geometry to one Ca(3), one Ca(4), one O(17), and one O(4) atom. The O(9)-O(17) bond length is 1.29 Å. In the tenth O site, O(10) is bonded in a 3-coordinate geometry to one Ca(7), one O(15), and one O(2) atom. The O(10)-O(15) bond length is 1.33 Å. In the eleventh O site, O(11) is bonded in a 6-coordinate geometry to one Ca(6), one Ca(7), one Ta(1), one O(12), one O(13), and one O(3) atom. The O(11)-O(12) bond length is 2.03 Å. The O(11)-O(13) bond length is 1.91 Å. In the twelfth O site, O(12) is bonded in a distorted single-bond geometry to one Ca(1), one Ca(7), and one O(11) atom. In the thirteenth O site, O(13) is bonded in a 2-coordinate geometry to one Ca(1), one Ta(2), and one O(11) atom. In the fourteenth O site, O(14) is bonded in a 4-coordinate geometry to one Ca(2), one Ca(6), one Ta(4), and one O(16) atom. The O(14)-O(16) bond length is 1.97 Å. In the fifteenth O site, O(15) is bonded in a 2-coordinate geometry to one Ca(3) and one O(10) atom. In the sixteenth O site, O(16) is bonded in a single-bond geometry to one Ca(5), one O(14), and one O(8) atom. In the seventeenth O site, O(17) is bonded in a 4-coordinate geometry to one Ca(3), one Ca(4), one Ca(8), and one O(9) atom. In the eighteenth O site, O(18) is bonded in a 1-coordinate geometry to one Ca(1) atom.