The structure described by Ca3SiO5 crystallizes in the trigonal R3m space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(1), one O(2), one O(8), one O(9), and two equivalent O(3) atoms to form distorted CaO6 octahedra that share corners with two equivalent Ca(1)O6 octahedra, corners with three equivalent Ca(3)O7 pentagonal bipyramids,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, edges with two equivalent Ca(1)O6 octahedra, and faces with two equivalent Ca(3)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 74°. In the second Ca site, Ca(2) is bonded in a distorted hexagonal planar geometry to one O(5), one O(6), one O(7), one O(9), and two equivalent O(2) atoms. In the third Ca site, Ca(3) is bonded to one O(4), one O(5), one O(8), two equivalent O(1), and two equivalent O(3) atoms to form distorted CaO7 pentagonal bipyramids that share corners with three equivalent Ca(1)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, edges with two equivalent Ca(3)O7 pentagonal bipyramids,  an edgeedge with one Si(1)O4 tetrahedra, faces with two equivalent Ca(1)O6 octahedra, and faces with two equivalent Ca(3)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 18-38°. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(7) and three equivalent O(3) atoms to form SiO4 tetrahedra that share corners with six equivalent Ca(1)O6 octahedra and edges with three equivalent Ca(3)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 59°. In the second Si site, Si(2) is bonded to one O(4) and three equivalent O(2) atoms to form SiO4 tetrahedra that share corners with three equivalent Ca(1)O6 octahedra and corners with three equivalent Ca(3)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 56°. In the third Si site, Si(3) is bonded to one O(6) and three equivalent O(1) atoms to form SiO4 tetrahedra that share corners with three equivalent Ca(1)O6 octahedra and corners with six equivalent Ca(3)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 63°. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Ca(1), two equivalent Ca(3), and one Si(3) atom. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Ca(1), two equivalent Ca(2), and one Si(2) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to two equivalent Ca(1), two equivalent Ca(3), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to three equivalent Ca(3) and one Si(2) atom. In the fifth O site, O(5) is bonded to three equivalent Ca(2) and three equivalent Ca(3) atoms to form OCa6 octahedra that share corners with three equivalent O(6)Ca3Si tetrahedra,  a faceface with one O(8)Ca6 octahedra, and  a faceface with one O(9)Ca6 octahedra. In the sixth O site, O(6) is bonded to three equivalent Ca(2) and one Si(3) atom to form distorted corner-sharing OCa3Si tetrahedra. The corner-sharing octahedral tilt angles range from 14-65°. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to three equivalent Ca(2) and one Si(1) atom. In the eighth O site, O(8) is bonded to three equivalent Ca(1) and three equivalent Ca(3) atoms to form a mixture of distorted face and corner-sharing OCa6 octahedra. The corner-sharing octahedral tilt angles are 9°. In the ninth O site, O(9) is bonded to three equivalent Ca(1) and three equivalent Ca(2) atoms to form OCa6 octahedra that share corners with three equivalent O(8)Ca6 octahedra, corners with three equivalent O(6)Ca3Si tetrahedra, and  a faceface with one O(5)Ca6 octahedra. The corner-sharing octahedral tilt angles are 9°. is represented by the CIF card [CIF]
data_Ca3SiO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.527
_cell_length_b   9.527
_cell_length_c   9.527
_cell_angle_alpha   43.688
_cell_angle_beta   43.688
_cell_angle_gamma   43.688
_symmetry_Int_Tables_number   1
_cell_volume   374.505
_cell_formula_units_Z   3
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  0.262  0.787  0.262  1.0
  Ca  Ca1  1  0.262  0.262  0.787  1.0
  Ca  Ca2  1  0.787  0.262  0.262  1.0
  Ca  Ca3  1  0.058  0.532  0.058  1.0
  Ca  Ca4  1  0.058  0.058  0.532  1.0
  Ca  Ca5  1  0.532  0.058  0.058  1.0
  Ca  Ca6  1  0.495  0.020  0.495  1.0
  Ca  Ca7  1  0.495  0.495  0.020  1.0
  Ca  Ca8  1  0.020  0.495  0.495  1.0
  Si  Si9  1  0.768  0.768  0.768  1.0
  Si  Si10  1  0.555  0.555  0.555  1.0
  Si  Si11  1  0.989  0.989  0.989  1.0
  O  O12  1  0.136  0.754  0.136  1.0
  O  O13  1  0.136  0.136  0.754  1.0
  O  O14  1  0.754  0.136  0.136  1.0
  O  O15  1  0.407  0.784  0.407  1.0
  O  O16  1  0.407  0.407  0.784  1.0
  O  O17  1  0.784  0.407  0.407  1.0
  O  O18  1  0.870  0.494  0.870  1.0
  O  O19  1  0.870  0.870  0.494  1.0
  O  O20  1  0.494  0.870  0.870  1.0
  O  O21  1  0.620  0.620  0.620  1.0
  O  O22  1  0.275  0.275  0.275  1.0
  O  O23  1  0.926  0.926  0.926  1.0
  O  O24  1  0.831  0.831  0.831  1.0
  O  O25  1  0.402  0.402  0.402  1.0
  O  O26  1  0.150  0.150  0.150  1.0
[/CIF]
.
The structure described by Ca3SiO5 crystallizes in the trigonal R3m space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(1), one O(2), one O(8), one O(9), and two equivalent O(3) atoms to form distorted CaO6 octahedra that share corners with two equivalent Ca(1)O6 octahedra, corners with three equivalent Ca(3)O7 pentagonal bipyramids,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, edges with two equivalent Ca(1)O6 octahedra, and faces with two equivalent Ca(3)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 74°. In the second Ca site, Ca(2) is bonded in a distorted hexagonal planar geometry to one O(5), one O(6), one O(7), one O(9), and two equivalent O(2) atoms. In the third Ca site, Ca(3) is bonded to one O(4), one O(5), one O(8), two equivalent O(1), and two equivalent O(3) atoms to form distorted CaO7 pentagonal bipyramids that share corners with three equivalent Ca(1)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, edges with two equivalent Ca(3)O7 pentagonal bipyramids,  an edgeedge with one Si(1)O4 tetrahedra, faces with two equivalent Ca(1)O6 octahedra, and faces with two equivalent Ca(3)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 18-38°. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(7) and three equivalent O(3) atoms to form SiO4 tetrahedra that share corners with six equivalent Ca(1)O6 octahedra and edges with three equivalent Ca(3)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 59°. In the second Si site, Si(2) is bonded to one O(4) and three equivalent O(2) atoms to form SiO4 tetrahedra that share corners with three equivalent Ca(1)O6 octahedra and corners with three equivalent Ca(3)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 56°. In the third Si site, Si(3) is bonded to one O(6) and three equivalent O(1) atoms to form SiO4 tetrahedra that share corners with three equivalent Ca(1)O6 octahedra and corners with six equivalent Ca(3)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 63°. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Ca(1), two equivalent Ca(3), and one Si(3) atom. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Ca(1), two equivalent Ca(2), and one Si(2) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to two equivalent Ca(1), two equivalent Ca(3), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to three equivalent Ca(3) and one Si(2) atom. In the fifth O site, O(5) is bonded to three equivalent Ca(2) and three equivalent Ca(3) atoms to form OCa6 octahedra that share corners with three equivalent O(6)Ca3Si tetrahedra,  a faceface with one O(8)Ca6 octahedra, and  a faceface with one O(9)Ca6 octahedra. In the sixth O site, O(6) is bonded to three equivalent Ca(2) and one Si(3) atom to form distorted corner-sharing OCa3Si tetrahedra. The corner-sharing octahedral tilt angles range from 14-65°. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to three equivalent Ca(2) and one Si(1) atom. In the eighth O site, O(8) is bonded to three equivalent Ca(1) and three equivalent Ca(3) atoms to form a mixture of distorted face and corner-sharing OCa6 octahedra. The corner-sharing octahedral tilt angles are 9°. In the ninth O site, O(9) is bonded to three equivalent Ca(1) and three equivalent Ca(2) atoms to form OCa6 octahedra that share corners with three equivalent O(8)Ca6 octahedra, corners with three equivalent O(6)Ca3Si tetrahedra, and  a faceface with one O(5)Ca6 octahedra. The corner-sharing octahedral tilt angles are 9°. is represented by the CIF card [CIF]
data_Ca3SiO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.527
_cell_length_b   9.527
_cell_length_c   9.527
_cell_angle_alpha   43.688
_cell_angle_beta   43.688
_cell_angle_gamma   43.688
_symmetry_Int_Tables_number   1
_cell_volume   374.505
_cell_formula_units_Z   3
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  0.262  0.787  0.262  1.0
  Ca  Ca1  1  0.262  0.262  0.787  1.0
  Ca  Ca2  1  0.787  0.262  0.262  1.0
  Ca  Ca3  1  0.058  0.532  0.058  1.0
  Ca  Ca4  1  0.058  0.058  0.532  1.0
  Ca  Ca5  1  0.532  0.058  0.058  1.0
  Ca  Ca6  1  0.495  0.020  0.495  1.0
  Ca  Ca7  1  0.495  0.495  0.020  1.0
  Ca  Ca8  1  0.020  0.495  0.495  1.0
  Si  Si9  1  0.768  0.768  0.768  1.0
  Si  Si10  1  0.555  0.555  0.555  1.0
  Si  Si11  1  0.989  0.989  0.989  1.0
  O  O12  1  0.136  0.754  0.136  1.0
  O  O13  1  0.136  0.136  0.754  1.0
  O  O14  1  0.754  0.136  0.136  1.0
  O  O15  1  0.407  0.784  0.407  1.0
  O  O16  1  0.407  0.407  0.784  1.0
  O  O17  1  0.784  0.407  0.407  1.0
  O  O18  1  0.870  0.494  0.870  1.0
  O  O19  1  0.870  0.870  0.494  1.0
  O  O20  1  0.494  0.870  0.870  1.0
  O  O21  1  0.620  0.620  0.620  1.0
  O  O22  1  0.275  0.275  0.275  1.0
  O  O23  1  0.926  0.926  0.926  1.0
  O  O24  1  0.831  0.831  0.831  1.0
  O  O25  1  0.402  0.402  0.402  1.0
  O  O26  1  0.150  0.150  0.150  1.0
[/CIF]
.