The structure described by Ca2SiO4 is Ilmenite-like structured and crystallizes in the orthorhombic Pnma space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(2), one O(3), and four equivalent O(1) atoms to form distorted CaO6 octahedra that share corners with four equivalent Ca(1)O6 octahedra, corners with four equivalent Ca(2)O6 octahedra, corners with four equivalent Si(1)O4 tetrahedra, edges with two equivalent Ca(2)O6 octahedra, and  an edgeedge with one Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 54-71°. In the second Ca site, Ca(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form CaO6 octahedra that share corners with four equivalent Ca(1)O6 octahedra, corners with two equivalent Si(1)O4 tetrahedra, edges with two equivalent Ca(1)O6 octahedra, edges with two equivalent Ca(2)O6 octahedra, and edges with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 62-71°. Si(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form SiO4 tetrahedra that share corners with two equivalent Ca(2)O6 octahedra, corners with four equivalent Ca(1)O6 octahedra,  an edgeedge with one Ca(1)O6 octahedra, and edges with two equivalent Ca(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 50-61°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Ca(2), two equivalent Ca(1), and one Si(1) 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(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Ca(1), two equivalent Ca(2), and one Si(1) atom. is represented by the CIF file [CIF]
data_Ca2SiO4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.087
_cell_length_b   6.755
_cell_length_c   11.237
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   386.127
_cell_formula_units_Z   4
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  0.490  0.750  0.780  1.0
  Ca  Ca1  1  0.990  0.250  0.720  1.0
  Ca  Ca2  1  0.510  0.250  0.220  1.0
  Ca  Ca3  1  0.010  0.750  0.280  1.0
  Ca  Ca4  1  0.500  0.500  0.500  1.0
  Ca  Ca5  1  0.000  0.500  0.000  1.0
  Ca  Ca6  1  0.500  0.000  0.500  1.0
  Ca  Ca7  1  0.000  0.000  0.000  1.0
  Si  Si8  1  0.927  0.750  0.596  1.0
  Si  Si9  1  0.427  0.250  0.904  1.0
  Si  Si10  1  0.073  0.250  0.404  1.0
  Si  Si11  1  0.573  0.750  0.096  1.0
  O  O12  1  0.203  0.445  0.338  1.0
  O  O13  1  0.703  0.555  0.162  1.0
  O  O14  1  0.797  0.945  0.662  1.0
  O  O15  1  0.297  0.055  0.838  1.0
  O  O16  1  0.797  0.555  0.662  1.0
  O  O17  1  0.297  0.445  0.838  1.0
  O  O18  1  0.203  0.055  0.338  1.0
  O  O19  1  0.703  0.945  0.162  1.0
  O  O20  1  0.798  0.750  0.461  1.0
  O  O21  1  0.298  0.250  0.039  1.0
  O  O22  1  0.202  0.250  0.539  1.0
  O  O23  1  0.702  0.750  0.961  1.0
  O  O24  1  0.253  0.750  0.093  1.0
  O  O25  1  0.753  0.250  0.407  1.0
  O  O26  1  0.747  0.250  0.907  1.0
  O  O27  1  0.247  0.750  0.593  1.0
[/CIF]
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The structure described by Ca2SiO4 is Ilmenite-like structured and crystallizes in the orthorhombic Pnma space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(2), one O(3), and four equivalent O(1) atoms to form distorted CaO6 octahedra that share corners with four equivalent Ca(1)O6 octahedra, corners with four equivalent Ca(2)O6 octahedra, corners with four equivalent Si(1)O4 tetrahedra, edges with two equivalent Ca(2)O6 octahedra, and  an edgeedge with one Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 54-71°. In the second Ca site, Ca(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form CaO6 octahedra that share corners with four equivalent Ca(1)O6 octahedra, corners with two equivalent Si(1)O4 tetrahedra, edges with two equivalent Ca(1)O6 octahedra, edges with two equivalent Ca(2)O6 octahedra, and edges with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 62-71°. Si(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form SiO4 tetrahedra that share corners with two equivalent Ca(2)O6 octahedra, corners with four equivalent Ca(1)O6 octahedra,  an edgeedge with one Ca(1)O6 octahedra, and edges with two equivalent Ca(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 50-61°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Ca(2), two equivalent Ca(1), and one Si(1) 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(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Ca(1), two equivalent Ca(2), and one Si(1) atom. is represented by the CIF file [CIF]
data_Ca2SiO4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.087
_cell_length_b   6.755
_cell_length_c   11.237
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   386.127
_cell_formula_units_Z   4
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  0.490  0.750  0.780  1.0
  Ca  Ca1  1  0.990  0.250  0.720  1.0
  Ca  Ca2  1  0.510  0.250  0.220  1.0
  Ca  Ca3  1  0.010  0.750  0.280  1.0
  Ca  Ca4  1  0.500  0.500  0.500  1.0
  Ca  Ca5  1  0.000  0.500  0.000  1.0
  Ca  Ca6  1  0.500  0.000  0.500  1.0
  Ca  Ca7  1  0.000  0.000  0.000  1.0
  Si  Si8  1  0.927  0.750  0.596  1.0
  Si  Si9  1  0.427  0.250  0.904  1.0
  Si  Si10  1  0.073  0.250  0.404  1.0
  Si  Si11  1  0.573  0.750  0.096  1.0
  O  O12  1  0.203  0.445  0.338  1.0
  O  O13  1  0.703  0.555  0.162  1.0
  O  O14  1  0.797  0.945  0.662  1.0
  O  O15  1  0.297  0.055  0.838  1.0
  O  O16  1  0.797  0.555  0.662  1.0
  O  O17  1  0.297  0.445  0.838  1.0
  O  O18  1  0.203  0.055  0.338  1.0
  O  O19  1  0.703  0.945  0.162  1.0
  O  O20  1  0.798  0.750  0.461  1.0
  O  O21  1  0.298  0.250  0.039  1.0
  O  O22  1  0.202  0.250  0.539  1.0
  O  O23  1  0.702  0.750  0.961  1.0
  O  O24  1  0.253  0.750  0.093  1.0
  O  O25  1  0.753  0.250  0.407  1.0
  O  O26  1  0.747  0.250  0.907  1.0
  O  O27  1  0.247  0.750  0.593  1.0
[/CIF]
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