The crystal structure described by SrCa7Ti2Mn6O21 crystallizes in the triclinic P1 space group. Sr(1) is bonded in a 10-coordinate geometry to one O(10), one O(14), one O(15), one O(18), one O(19), one O(2), one O(4), one O(7), one O(8), and one O(9) atom. There are seven inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 4-coordinate geometry to one O(10), one O(18), one O(19), and one O(8) atom. In the second Ca site, Ca(2) is bonded in a 8-coordinate geometry to one O(10), one O(16), one O(17), one O(2), one O(20), one O(21), one O(7), and one O(9) atom. In the third Ca site, Ca(3) is bonded in a 9-coordinate geometry to one O(10), one O(17), one O(21), one O(3), one O(5), one O(6), one O(7), one O(8), and one O(9) atom. In the fourth Ca site, Ca(4) is bonded in a 8-coordinate geometry to one O(11), one O(12), one O(13), one O(14), one O(15), one O(19), one O(2), and one O(4) atom. In the fifth Ca site, Ca(5) is bonded in a 6-coordinate geometry to one O(1), one O(15), one O(18), one O(19), one O(3), and one O(5) atom. In the sixth Ca site, Ca(6) is bonded in a 7-coordinate geometry to one O(11), one O(12), one O(13), one O(16), one O(20), one O(21), and one O(4) atom. In the seventh Ca site, Ca(7) is bonded in a 6-coordinate geometry to one O(1), one O(11), one O(13), one O(3), one O(5), and one O(6) atom. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(1), one O(14), one O(16), and one O(7) atom to form TiO4 tetrahedra that share corners with two equivalent Mn(2)O6 octahedra,  a cornercorner with one Mn(1)O5 square pyramid, and  a cornercorner with one Ti(2)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 40-48°. In the second Ti site, Ti(2) is bonded to one O(18), one O(20), one O(4), one O(5), and one O(7) atom to form TiO5 trigonal bipyramids that share corners with two equivalent Mn(4)O6 octahedra,  a cornercorner with one Ti(1)O4 tetrahedra, and corners with two equivalent Mn(5)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 31-44°. There are six inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(1), one O(11), one O(15), one O(17), and one O(8) atom to form MnO5 square pyramids that share corners with two equivalent Mn(3)O6 octahedra, corners with two equivalent Mn(4)O6 octahedra, and  a cornercorner with one Ti(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 16-23°. In the second Mn site, Mn(2) is bonded to one O(12), one O(14), one O(16), one O(2), one O(3), and one O(9) atom to form distorted MnO6 octahedra that share corners with two equivalent Mn(3)O6 octahedra, corners with two equivalent Ti(1)O4 tetrahedra, and corners with two equivalent Mn(5)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 10-15°. In the third Mn site, Mn(3) is bonded to one O(10), one O(13), one O(15), one O(17), one O(2), and one O(3) atom to form MnO6 octahedra that share corners with two equivalent Mn(2)O6 octahedra, corners with two equivalent Mn(1)O5 square pyramids, and corners with two equivalent Mn(6)O5 square pyramids. The corner-sharing octahedral tilt angles range from 10-15°. In the fourth Mn site, Mn(4) is bonded to one O(11), one O(19), one O(21), one O(4), one O(5), and one O(8) atom to form MnO6 octahedra that share corners with two equivalent Mn(1)O5 square pyramids, corners with two equivalent Mn(6)O5 square pyramids, and corners with two equivalent Ti(2)O5 trigonal bipyramids. In the fifth Mn site, Mn(5) is bonded to one O(12), one O(18), one O(20), one O(6), and one O(9) atom to form MnO5 trigonal bipyramids that share corners with two equivalent Mn(2)O6 octahedra,  a cornercorner with one Mn(6)O5 square pyramid, and corners with two equivalent Ti(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 9-29°. In the sixth Mn site, Mn(6) is bonded to one O(10), one O(13), one O(19), one O(21), and one O(6) atom to form MnO5 square pyramids that share corners with two equivalent Mn(3)O6 octahedra, corners with two equivalent Mn(4)O6 octahedra, and  a cornercorner with one Mn(5)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 14-31°. There are twenty-one inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Ca(5), one Ca(7), one Ti(1), and one Mn(1) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Sr(1), one Ca(2), one Ca(4), one Mn(2), and one Mn(3) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Ca(3), one Ca(5), one Ca(7), one Mn(2), and one Mn(3) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Sr(1), one Ca(4), one Ca(6), one Ti(2), and one Mn(4) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Ca(3), one Ca(5), one Ca(7), one Ti(2), and one Mn(4) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Ca(3), one Ca(7), one Mn(5), and one Mn(6) atom. In the seventh O site, O(7) is bonded in a distorted linear geometry to one Sr(1), one Ca(2), one Ca(3), one Ti(1), and one Ti(2) atom. In the eighth O site, O(8) is bonded in a 5-coordinate geometry to one Sr(1), one Ca(1), one Ca(3), one Mn(1), and one Mn(4) atom. In the ninth O site, O(9) is bonded in a 5-coordinate geometry to one Sr(1), one Ca(2), one Ca(3), one Mn(2), and one Mn(5) atom. In the tenth O site, O(10) is bonded in a 6-coordinate geometry to one Sr(1), one Ca(1), one Ca(2), one Ca(3), one Mn(3), and one Mn(6) atom. In the eleventh O site, O(11) is bonded in a 4-coordinate geometry to one Ca(4), one Ca(6), one Ca(7), one Mn(1), and one Mn(4) atom. In the twelfth O site, O(12) is bonded in a 4-coordinate geometry to one Ca(4), one Ca(6), one Mn(2), and one Mn(5) atom. In the thirteenth O site, O(13) is bonded in a 5-coordinate geometry to one Ca(4), one Ca(6), one Ca(7), one Mn(3), and one Mn(6) atom. In the fourteenth O site, O(14) is bonded in a 4-coordinate geometry to one Sr(1), one Ca(4), one Ti(1), and one Mn(2) atom. In the fifteenth O site, O(15) is bonded in a 4-coordinate geometry to one Sr(1), one Ca(4), one Ca(5), one Mn(1), and one Mn(3) atom. In the sixteenth O site, O(16) is bonded in a 4-coordinate geometry to one Ca(2), one Ca(6), one Ti(1), and one Mn(2) atom. In the seventeenth O site, O(17) is bonded in a 4-coordinate geometry to one Ca(2), one Ca(3), one Mn(1), and one Mn(3) atom. In the eighteenth O site, O(18) is bonded in a 5-coordinate geometry to one Sr(1), one Ca(1), one Ca(5), one Ti(2), and one Mn(5) atom. In the nineteenth O site, O(19) is bonded in a 5-coordinate geometry to one Sr(1), one Ca(1), one Ca(4), one Ca(5), one Mn(4), and one Mn(6) atom. In the twentieth O site, O(20) is bonded in a 4-coordinate geometry to one Ca(2), one Ca(6), one Ti(2), and one Mn(5) atom. In the twenty-first O site, O(21) is bonded in a distorted trigonal bipyramidal geometry to one Ca(2), one Ca(3), one Ca(6), one Mn(4), and one Mn(6) atom. is represented by the CIF file [CIF]
data_SrCa7Ti2Mn6O21
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.879
_cell_length_b   7.746
_cell_length_c   7.850
_cell_angle_alpha   89.936
_cell_angle_beta   89.365
_cell_angle_gamma   90.518
_symmetry_Int_Tables_number   1
_cell_volume   479.082
_cell_formula_units_Z   1
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
  Sr  Sr0  1  0.241  0.260  0.243  1.0
  Ca  Ca1  1  0.282  0.265  0.707  1.0
  Ca  Ca2  1  0.224  0.718  0.246  1.0
  Ca  Ca3  1  0.265  0.730  0.698  1.0
  Ca  Ca4  1  0.768  0.271  0.282  1.0
  Ca  Ca5  1  0.746  0.238  0.729  1.0
  Ca  Ca6  1  0.719  0.748  0.253  1.0
  Ca  Ca7  1  0.754  0.745  0.706  1.0
  Ti  Ti8  1  0.017  0.986  0.988  1.0
  Ti  Ti9  1  0.487  0.992  0.992  1.0
  Mn  Mn10  1  0.006  0.998  0.511  1.0
  Mn  Mn11  1  0.980  0.504  0.015  1.0
  Mn  Mn12  1  0.998  0.501  0.507  1.0
  Mn  Mn13  1  0.513  0.001  0.477  1.0
  Mn  Mn14  1  0.492  0.502  0.984  1.0
  Mn  Mn15  1  0.506  0.508  0.499  1.0
  O  O16  1  0.949  0.985  0.771  1.0
  O  O17  1  0.017  0.485  0.262  1.0
  O  O18  1  0.971  0.517  0.762  1.0
  O  O19  1  0.582  0.046  0.198  1.0
  O  O20  1  0.566  0.977  0.769  1.0
  O  O21  1  0.507  0.555  0.741  1.0
  O  O22  1  0.249  0.973  0.007  1.0
  O  O23  1  0.258  0.037  0.509  1.0
  O  O24  1  0.243  0.519  0.014  1.0
  O  O25  1  0.265  0.473  0.499  1.0
  O  O26  1  0.765  0.959  0.470  1.0
  O  O27  1  0.725  0.476  0.057  1.0
  O  O28  1  0.742  0.540  0.472  1.0
  O  O29  1  0.969  0.191  0.082  1.0
  O  O30  1  0.968  0.246  0.517  1.0
  O  O31  1  0.955  0.790  0.093  1.0
  O  O32  1  0.050  0.753  0.499  1.0
  O  O33  1  0.462  0.255  0.948  1.0
  O  O34  1  0.540  0.256  0.509  1.0
  O  O35  1  0.507  0.747  0.043  1.0
  O  O36  1  0.463  0.751  0.439  1.0
[/CIF]
.
The crystal structure described by SrCa7Ti2Mn6O21 crystallizes in the triclinic P1 space group. Sr(1) is bonded in a 10-coordinate geometry to one O(10), one O(14), one O(15), one O(18), one O(19), one O(2), one O(4), one O(7), one O(8), and one O(9) atom. There are seven inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 4-coordinate geometry to one O(10), one O(18), one O(19), and one O(8) atom. In the second Ca site, Ca(2) is bonded in a 8-coordinate geometry to one O(10), one O(16), one O(17), one O(2), one O(20), one O(21), one O(7), and one O(9) atom. In the third Ca site, Ca(3) is bonded in a 9-coordinate geometry to one O(10), one O(17), one O(21), one O(3), one O(5), one O(6), one O(7), one O(8), and one O(9) atom. In the fourth Ca site, Ca(4) is bonded in a 8-coordinate geometry to one O(11), one O(12), one O(13), one O(14), one O(15), one O(19), one O(2), and one O(4) atom. In the fifth Ca site, Ca(5) is bonded in a 6-coordinate geometry to one O(1), one O(15), one O(18), one O(19), one O(3), and one O(5) atom. In the sixth Ca site, Ca(6) is bonded in a 7-coordinate geometry to one O(11), one O(12), one O(13), one O(16), one O(20), one O(21), and one O(4) atom. In the seventh Ca site, Ca(7) is bonded in a 6-coordinate geometry to one O(1), one O(11), one O(13), one O(3), one O(5), and one O(6) atom. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(1), one O(14), one O(16), and one O(7) atom to form TiO4 tetrahedra that share corners with two equivalent Mn(2)O6 octahedra,  a cornercorner with one Mn(1)O5 square pyramid, and  a cornercorner with one Ti(2)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 40-48°. In the second Ti site, Ti(2) is bonded to one O(18), one O(20), one O(4), one O(5), and one O(7) atom to form TiO5 trigonal bipyramids that share corners with two equivalent Mn(4)O6 octahedra,  a cornercorner with one Ti(1)O4 tetrahedra, and corners with two equivalent Mn(5)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 31-44°. There are six inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(1), one O(11), one O(15), one O(17), and one O(8) atom to form MnO5 square pyramids that share corners with two equivalent Mn(3)O6 octahedra, corners with two equivalent Mn(4)O6 octahedra, and  a cornercorner with one Ti(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 16-23°. In the second Mn site, Mn(2) is bonded to one O(12), one O(14), one O(16), one O(2), one O(3), and one O(9) atom to form distorted MnO6 octahedra that share corners with two equivalent Mn(3)O6 octahedra, corners with two equivalent Ti(1)O4 tetrahedra, and corners with two equivalent Mn(5)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 10-15°. In the third Mn site, Mn(3) is bonded to one O(10), one O(13), one O(15), one O(17), one O(2), and one O(3) atom to form MnO6 octahedra that share corners with two equivalent Mn(2)O6 octahedra, corners with two equivalent Mn(1)O5 square pyramids, and corners with two equivalent Mn(6)O5 square pyramids. The corner-sharing octahedral tilt angles range from 10-15°. In the fourth Mn site, Mn(4) is bonded to one O(11), one O(19), one O(21), one O(4), one O(5), and one O(8) atom to form MnO6 octahedra that share corners with two equivalent Mn(1)O5 square pyramids, corners with two equivalent Mn(6)O5 square pyramids, and corners with two equivalent Ti(2)O5 trigonal bipyramids. In the fifth Mn site, Mn(5) is bonded to one O(12), one O(18), one O(20), one O(6), and one O(9) atom to form MnO5 trigonal bipyramids that share corners with two equivalent Mn(2)O6 octahedra,  a cornercorner with one Mn(6)O5 square pyramid, and corners with two equivalent Ti(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 9-29°. In the sixth Mn site, Mn(6) is bonded to one O(10), one O(13), one O(19), one O(21), and one O(6) atom to form MnO5 square pyramids that share corners with two equivalent Mn(3)O6 octahedra, corners with two equivalent Mn(4)O6 octahedra, and  a cornercorner with one Mn(5)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 14-31°. There are twenty-one inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Ca(5), one Ca(7), one Ti(1), and one Mn(1) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Sr(1), one Ca(2), one Ca(4), one Mn(2), and one Mn(3) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Ca(3), one Ca(5), one Ca(7), one Mn(2), and one Mn(3) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Sr(1), one Ca(4), one Ca(6), one Ti(2), and one Mn(4) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Ca(3), one Ca(5), one Ca(7), one Ti(2), and one Mn(4) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Ca(3), one Ca(7), one Mn(5), and one Mn(6) atom. In the seventh O site, O(7) is bonded in a distorted linear geometry to one Sr(1), one Ca(2), one Ca(3), one Ti(1), and one Ti(2) atom. In the eighth O site, O(8) is bonded in a 5-coordinate geometry to one Sr(1), one Ca(1), one Ca(3), one Mn(1), and one Mn(4) atom. In the ninth O site, O(9) is bonded in a 5-coordinate geometry to one Sr(1), one Ca(2), one Ca(3), one Mn(2), and one Mn(5) atom. In the tenth O site, O(10) is bonded in a 6-coordinate geometry to one Sr(1), one Ca(1), one Ca(2), one Ca(3), one Mn(3), and one Mn(6) atom. In the eleventh O site, O(11) is bonded in a 4-coordinate geometry to one Ca(4), one Ca(6), one Ca(7), one Mn(1), and one Mn(4) atom. In the twelfth O site, O(12) is bonded in a 4-coordinate geometry to one Ca(4), one Ca(6), one Mn(2), and one Mn(5) atom. In the thirteenth O site, O(13) is bonded in a 5-coordinate geometry to one Ca(4), one Ca(6), one Ca(7), one Mn(3), and one Mn(6) atom. In the fourteenth O site, O(14) is bonded in a 4-coordinate geometry to one Sr(1), one Ca(4), one Ti(1), and one Mn(2) atom. In the fifteenth O site, O(15) is bonded in a 4-coordinate geometry to one Sr(1), one Ca(4), one Ca(5), one Mn(1), and one Mn(3) atom. In the sixteenth O site, O(16) is bonded in a 4-coordinate geometry to one Ca(2), one Ca(6), one Ti(1), and one Mn(2) atom. In the seventeenth O site, O(17) is bonded in a 4-coordinate geometry to one Ca(2), one Ca(3), one Mn(1), and one Mn(3) atom. In the eighteenth O site, O(18) is bonded in a 5-coordinate geometry to one Sr(1), one Ca(1), one Ca(5), one Ti(2), and one Mn(5) atom. In the nineteenth O site, O(19) is bonded in a 5-coordinate geometry to one Sr(1), one Ca(1), one Ca(4), one Ca(5), one Mn(4), and one Mn(6) atom. In the twentieth O site, O(20) is bonded in a 4-coordinate geometry to one Ca(2), one Ca(6), one Ti(2), and one Mn(5) atom. In the twenty-first O site, O(21) is bonded in a distorted trigonal bipyramidal geometry to one Ca(2), one Ca(3), one Ca(6), one Mn(4), and one Mn(6) atom. is represented by the CIF file [CIF]
data_SrCa7Ti2Mn6O21
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.879
_cell_length_b   7.746
_cell_length_c   7.850
_cell_angle_alpha   89.936
_cell_angle_beta   89.365
_cell_angle_gamma   90.518
_symmetry_Int_Tables_number   1
_cell_volume   479.082
_cell_formula_units_Z   1
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
  Sr  Sr0  1  0.241  0.260  0.243  1.0
  Ca  Ca1  1  0.282  0.265  0.707  1.0
  Ca  Ca2  1  0.224  0.718  0.246  1.0
  Ca  Ca3  1  0.265  0.730  0.698  1.0
  Ca  Ca4  1  0.768  0.271  0.282  1.0
  Ca  Ca5  1  0.746  0.238  0.729  1.0
  Ca  Ca6  1  0.719  0.748  0.253  1.0
  Ca  Ca7  1  0.754  0.745  0.706  1.0
  Ti  Ti8  1  0.017  0.986  0.988  1.0
  Ti  Ti9  1  0.487  0.992  0.992  1.0
  Mn  Mn10  1  0.006  0.998  0.511  1.0
  Mn  Mn11  1  0.980  0.504  0.015  1.0
  Mn  Mn12  1  0.998  0.501  0.507  1.0
  Mn  Mn13  1  0.513  0.001  0.477  1.0
  Mn  Mn14  1  0.492  0.502  0.984  1.0
  Mn  Mn15  1  0.506  0.508  0.499  1.0
  O  O16  1  0.949  0.985  0.771  1.0
  O  O17  1  0.017  0.485  0.262  1.0
  O  O18  1  0.971  0.517  0.762  1.0
  O  O19  1  0.582  0.046  0.198  1.0
  O  O20  1  0.566  0.977  0.769  1.0
  O  O21  1  0.507  0.555  0.741  1.0
  O  O22  1  0.249  0.973  0.007  1.0
  O  O23  1  0.258  0.037  0.509  1.0
  O  O24  1  0.243  0.519  0.014  1.0
  O  O25  1  0.265  0.473  0.499  1.0
  O  O26  1  0.765  0.959  0.470  1.0
  O  O27  1  0.725  0.476  0.057  1.0
  O  O28  1  0.742  0.540  0.472  1.0
  O  O29  1  0.969  0.191  0.082  1.0
  O  O30  1  0.968  0.246  0.517  1.0
  O  O31  1  0.955  0.790  0.093  1.0
  O  O32  1  0.050  0.753  0.499  1.0
  O  O33  1  0.462  0.255  0.948  1.0
  O  O34  1  0.540  0.256  0.509  1.0
  O  O35  1  0.507  0.747  0.043  1.0
  O  O36  1  0.463  0.751  0.439  1.0
[/CIF]
.