The structure described by Na2Ti3Cr(PO4)6 crystallizes in the trigonal R3 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a distorted hexagonal planar geometry to three equivalent O(2) and three equivalent O(3) atoms. In the second Na site, Na(2) is bonded in a distorted hexagonal planar geometry to three equivalent O(5) and three equivalent O(6) atoms. There are three inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to three equivalent O(5) and three equivalent O(7) atoms to form TiO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. In the second Ti site, Ti(2) is bonded to three equivalent O(4) and three equivalent O(6) atoms to form TiO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. In the third Ti site, Ti(3) is bonded to three equivalent O(1) and three equivalent O(3) atoms to form TiO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. Cr(1) is bonded to three equivalent O(2) and three equivalent O(8) atoms to form CrO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form PO4 tetrahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Ti(2)O6 octahedra,  a cornercorner with one Ti(3)O6 octahedra, and  a cornercorner with one Cr(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 24-40°. In the second P site, P(2) is bonded to one O(3), one O(6), one O(7), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Ti(2)O6 octahedra,  a cornercorner with one Ti(3)O6 octahedra, and  a cornercorner with one Cr(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 28-38°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Ti(3) and one P(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Na(1), one Cr(1), and one P(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Na(1), one Ti(3), and one P(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Ti(2) and one P(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Na(2), one Ti(1), and one P(1) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Na(2), one Ti(2), and one P(2) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Ti(1) and one P(2) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Cr(1) and one P(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na2Ti3Cr(PO4)6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.912
_cell_length_b   8.912
_cell_length_c   8.912
_cell_angle_alpha   57.098
_cell_angle_beta   57.098
_cell_angle_gamma   57.098
_symmetry_Int_Tables_number   1
_cell_volume   466.959
_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
  Na  Na0  1  0.999  0.999  0.999  1.0
  Na  Na1  1  0.500  0.500  0.500  1.0
  Ti  Ti2  1  0.647  0.647  0.647  1.0
  Ti  Ti3  1  0.353  0.353  0.353  1.0
  Ti  Ti4  1  0.144  0.144  0.144  1.0
  Cr  Cr5  1  0.856  0.856  0.856  1.0
  P  P6  1  0.965  0.246  0.538  1.0
  P  P7  1  0.463  0.035  0.751  1.0
  P  P8  1  0.751  0.463  0.035  1.0
  P  P9  1  0.246  0.538  0.965  1.0
  P  P10  1  0.538  0.965  0.246  1.0
  P  P11  1  0.035  0.751  0.463  1.0
  O  O12  1  0.000  0.198  0.377  1.0
  O  O13  1  0.909  0.095  0.736  1.0
  O  O14  1  0.904  0.266  0.093  1.0
  O  O15  1  0.511  0.149  0.252  1.0
  O  O16  1  0.799  0.440  0.536  1.0
  O  O17  1  0.467  0.200  0.555  1.0
  O  O18  1  0.746  0.488  0.851  1.0
  O  O19  1  0.008  0.798  0.620  1.0
  O  O20  1  0.798  0.620  0.008  1.0
  O  O21  1  0.266  0.093  0.904  1.0
  O  O22  1  0.851  0.746  0.488  1.0
  O  O23  1  0.555  0.467  0.200  1.0
  O  O24  1  0.440  0.536  0.799  1.0
  O  O25  1  0.149  0.252  0.511  1.0
  O  O26  1  0.736  0.909  0.095  1.0
  O  O27  1  0.198  0.377  0.000  1.0
  O  O28  1  0.252  0.511  0.149  1.0
  O  O29  1  0.536  0.799  0.440  1.0
  O  O30  1  0.200  0.555  0.467  1.0
  O  O31  1  0.488  0.851  0.746  1.0
  O  O32  1  0.620  0.008  0.798  1.0
  O  O33  1  0.377  0.000  0.198  1.0
  O  O34  1  0.095  0.736  0.909  1.0
  O  O35  1  0.093  0.904  0.266  1.0
[/CIF]
.
The structure described by Na2Ti3Cr(PO4)6 crystallizes in the trigonal R3 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a distorted hexagonal planar geometry to three equivalent O(2) and three equivalent O(3) atoms. In the second Na site, Na(2) is bonded in a distorted hexagonal planar geometry to three equivalent O(5) and three equivalent O(6) atoms. There are three inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to three equivalent O(5) and three equivalent O(7) atoms to form TiO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. In the second Ti site, Ti(2) is bonded to three equivalent O(4) and three equivalent O(6) atoms to form TiO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. In the third Ti site, Ti(3) is bonded to three equivalent O(1) and three equivalent O(3) atoms to form TiO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. Cr(1) is bonded to three equivalent O(2) and three equivalent O(8) atoms to form CrO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form PO4 tetrahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Ti(2)O6 octahedra,  a cornercorner with one Ti(3)O6 octahedra, and  a cornercorner with one Cr(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 24-40°. In the second P site, P(2) is bonded to one O(3), one O(6), one O(7), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Ti(2)O6 octahedra,  a cornercorner with one Ti(3)O6 octahedra, and  a cornercorner with one Cr(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 28-38°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Ti(3) and one P(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Na(1), one Cr(1), and one P(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Na(1), one Ti(3), and one P(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Ti(2) and one P(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Na(2), one Ti(1), and one P(1) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Na(2), one Ti(2), and one P(2) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Ti(1) and one P(2) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Cr(1) and one P(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na2Ti3Cr(PO4)6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.912
_cell_length_b   8.912
_cell_length_c   8.912
_cell_angle_alpha   57.098
_cell_angle_beta   57.098
_cell_angle_gamma   57.098
_symmetry_Int_Tables_number   1
_cell_volume   466.959
_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
  Na  Na0  1  0.999  0.999  0.999  1.0
  Na  Na1  1  0.500  0.500  0.500  1.0
  Ti  Ti2  1  0.647  0.647  0.647  1.0
  Ti  Ti3  1  0.353  0.353  0.353  1.0
  Ti  Ti4  1  0.144  0.144  0.144  1.0
  Cr  Cr5  1  0.856  0.856  0.856  1.0
  P  P6  1  0.965  0.246  0.538  1.0
  P  P7  1  0.463  0.035  0.751  1.0
  P  P8  1  0.751  0.463  0.035  1.0
  P  P9  1  0.246  0.538  0.965  1.0
  P  P10  1  0.538  0.965  0.246  1.0
  P  P11  1  0.035  0.751  0.463  1.0
  O  O12  1  0.000  0.198  0.377  1.0
  O  O13  1  0.909  0.095  0.736  1.0
  O  O14  1  0.904  0.266  0.093  1.0
  O  O15  1  0.511  0.149  0.252  1.0
  O  O16  1  0.799  0.440  0.536  1.0
  O  O17  1  0.467  0.200  0.555  1.0
  O  O18  1  0.746  0.488  0.851  1.0
  O  O19  1  0.008  0.798  0.620  1.0
  O  O20  1  0.798  0.620  0.008  1.0
  O  O21  1  0.266  0.093  0.904  1.0
  O  O22  1  0.851  0.746  0.488  1.0
  O  O23  1  0.555  0.467  0.200  1.0
  O  O24  1  0.440  0.536  0.799  1.0
  O  O25  1  0.149  0.252  0.511  1.0
  O  O26  1  0.736  0.909  0.095  1.0
  O  O27  1  0.198  0.377  0.000  1.0
  O  O28  1  0.252  0.511  0.149  1.0
  O  O29  1  0.536  0.799  0.440  1.0
  O  O30  1  0.200  0.555  0.467  1.0
  O  O31  1  0.488  0.851  0.746  1.0
  O  O32  1  0.620  0.008  0.798  1.0
  O  O33  1  0.377  0.000  0.198  1.0
  O  O34  1  0.095  0.736  0.909  1.0
  O  O35  1  0.093  0.904  0.266  1.0
[/CIF]
.