The compound described by K3Ca(PO4)2 crystallizes in the monoclinic C2/m space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a distorted q6 geometry to two equivalent O(2), four equivalent O(1), and four equivalent O(3) atoms. In the second K site, K(2) is bonded in a 9-coordinate geometry to one O(1), two equivalent O(2), and six equivalent O(3) atoms. Ca(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form CaO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra. P(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form PO4 tetrahedra that share corners with three equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 13-28°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 1-coordinate geometry to one K(2), two equivalent K(1), and one P(1) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one K(1), two equivalent K(2), one Ca(1), and one P(1) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one K(1), three equivalent K(2), one Ca(1), and one P(1) atom. is represented by the CIF file [CIF]
data_K3Ca(PO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.818
_cell_length_b   5.818
_cell_length_c   7.540
_cell_angle_alpha   86.742
_cell_angle_beta   86.742
_cell_angle_gamma   59.397
_symmetry_Int_Tables_number   1
_cell_volume   219.165
_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
  K  K0  1  0.000  0.000  0.000  1.0
  K  K1  1  0.332  0.332  0.700  1.0
  K  K2  1  0.668  0.668  0.300  1.0
  Ca  Ca3  1  0.000  0.000  0.500  1.0
  P  P4  1  0.341  0.341  0.250  1.0
  P  P5  1  0.659  0.659  0.750  1.0
  O  O6  1  0.362  0.362  0.043  1.0
  O  O7  1  0.638  0.638  0.957  1.0
  O  O8  1  0.189  0.189  0.295  1.0
  O  O9  1  0.811  0.811  0.705  1.0
  O  O10  1  0.184  0.624  0.328  1.0
  O  O11  1  0.624  0.184  0.328  1.0
  O  O12  1  0.816  0.376  0.672  1.0
  O  O13  1  0.376  0.816  0.672  1.0
[/CIF]
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The compound described by K3Ca(PO4)2 crystallizes in the monoclinic C2/m space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a distorted q6 geometry to two equivalent O(2), four equivalent O(1), and four equivalent O(3) atoms. In the second K site, K(2) is bonded in a 9-coordinate geometry to one O(1), two equivalent O(2), and six equivalent O(3) atoms. Ca(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form CaO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra. P(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form PO4 tetrahedra that share corners with three equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 13-28°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 1-coordinate geometry to one K(2), two equivalent K(1), and one P(1) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one K(1), two equivalent K(2), one Ca(1), and one P(1) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one K(1), three equivalent K(2), one Ca(1), and one P(1) atom. is represented by the CIF file [CIF]
data_K3Ca(PO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.818
_cell_length_b   5.818
_cell_length_c   7.540
_cell_angle_alpha   86.742
_cell_angle_beta   86.742
_cell_angle_gamma   59.397
_symmetry_Int_Tables_number   1
_cell_volume   219.165
_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
  K  K0  1  0.000  0.000  0.000  1.0
  K  K1  1  0.332  0.332  0.700  1.0
  K  K2  1  0.668  0.668  0.300  1.0
  Ca  Ca3  1  0.000  0.000  0.500  1.0
  P  P4  1  0.341  0.341  0.250  1.0
  P  P5  1  0.659  0.659  0.750  1.0
  O  O6  1  0.362  0.362  0.043  1.0
  O  O7  1  0.638  0.638  0.957  1.0
  O  O8  1  0.189  0.189  0.295  1.0
  O  O9  1  0.811  0.811  0.705  1.0
  O  O10  1  0.184  0.624  0.328  1.0
  O  O11  1  0.624  0.184  0.328  1.0
  O  O12  1  0.816  0.376  0.672  1.0
  O  O13  1  0.376  0.816  0.672  1.0
[/CIF]
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