The structure described by KNiPO4 crystallizes in the orthorhombic Pna2_1 space group. K(1) is bonded in a 7-coordinate geometry to one O(2), two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms. Ni(1) is bonded to one O(1), one O(3), one O(4), and two equivalent O(2) atoms to form distorted NiO5 trigonal bipyramids that share corners with three equivalent P(1)O4 tetrahedra, corners with two equivalent Ni(1)O5 trigonal bipyramids, and  an edgeedge with one P(1)O4 tetrahedra. P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share corners with three equivalent Ni(1)O5 trigonal bipyramids and  an edgeedge with one Ni(1)O5 trigonal bipyramid. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to two equivalent K(1), one Ni(1), and one P(1) atom. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one K(1), two equivalent Ni(1), and one P(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to two equivalent K(1), one Ni(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to two equivalent K(1), one Ni(1), and one P(1) atom. is represented by the CIF file [CIF]
data_KNiPO4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.975
_cell_length_b   8.722
_cell_length_c   9.363
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   406.236
_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
  K  K0  1  0.519  0.499  0.183  1.0
  K  K1  1  0.019  0.501  0.817  1.0
  K  K2  1  0.019  0.001  0.683  1.0
  K  K3  1  0.519  0.999  0.317  1.0
  Ni  Ni4  1  0.999  0.655  0.458  1.0
  Ni  Ni5  1  0.499  0.345  0.542  1.0
  Ni  Ni6  1  0.499  0.845  0.958  1.0
  Ni  Ni7  1  0.999  0.155  0.042  1.0
  P  P8  1  0.064  0.791  0.126  1.0
  P  P9  1  0.564  0.209  0.874  1.0
  P  P10  1  0.564  0.709  0.626  1.0
  P  P11  1  0.064  0.291  0.374  1.0
  O  O12  1  0.144  0.755  0.282  1.0
  O  O13  1  0.644  0.245  0.718  1.0
  O  O14  1  0.644  0.745  0.782  1.0
  O  O15  1  0.144  0.255  0.218  1.0
  O  O16  1  0.186  0.453  0.416  1.0
  O  O17  1  0.686  0.547  0.584  1.0
  O  O18  1  0.686  0.047  0.916  1.0
  O  O19  1  0.186  0.953  0.084  1.0
  O  O20  1  0.755  0.287  0.387  1.0
  O  O21  1  0.255  0.713  0.613  1.0
  O  O22  1  0.255  0.213  0.887  1.0
  O  O23  1  0.755  0.787  0.113  1.0
  O  O24  1  0.211  0.683  0.018  1.0
  O  O25  1  0.711  0.317  0.982  1.0
  O  O26  1  0.711  0.817  0.518  1.0
  O  O27  1  0.211  0.183  0.482  1.0
[/CIF]
.
The structure described by KNiPO4 crystallizes in the orthorhombic Pna2_1 space group. K(1) is bonded in a 7-coordinate geometry to one O(2), two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms. Ni(1) is bonded to one O(1), one O(3), one O(4), and two equivalent O(2) atoms to form distorted NiO5 trigonal bipyramids that share corners with three equivalent P(1)O4 tetrahedra, corners with two equivalent Ni(1)O5 trigonal bipyramids, and  an edgeedge with one P(1)O4 tetrahedra. P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share corners with three equivalent Ni(1)O5 trigonal bipyramids and  an edgeedge with one Ni(1)O5 trigonal bipyramid. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to two equivalent K(1), one Ni(1), and one P(1) atom. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one K(1), two equivalent Ni(1), and one P(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to two equivalent K(1), one Ni(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to two equivalent K(1), one Ni(1), and one P(1) atom. is represented by the CIF file [CIF]
data_KNiPO4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.975
_cell_length_b   8.722
_cell_length_c   9.363
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   406.236
_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
  K  K0  1  0.519  0.499  0.183  1.0
  K  K1  1  0.019  0.501  0.817  1.0
  K  K2  1  0.019  0.001  0.683  1.0
  K  K3  1  0.519  0.999  0.317  1.0
  Ni  Ni4  1  0.999  0.655  0.458  1.0
  Ni  Ni5  1  0.499  0.345  0.542  1.0
  Ni  Ni6  1  0.499  0.845  0.958  1.0
  Ni  Ni7  1  0.999  0.155  0.042  1.0
  P  P8  1  0.064  0.791  0.126  1.0
  P  P9  1  0.564  0.209  0.874  1.0
  P  P10  1  0.564  0.709  0.626  1.0
  P  P11  1  0.064  0.291  0.374  1.0
  O  O12  1  0.144  0.755  0.282  1.0
  O  O13  1  0.644  0.245  0.718  1.0
  O  O14  1  0.644  0.745  0.782  1.0
  O  O15  1  0.144  0.255  0.218  1.0
  O  O16  1  0.186  0.453  0.416  1.0
  O  O17  1  0.686  0.547  0.584  1.0
  O  O18  1  0.686  0.047  0.916  1.0
  O  O19  1  0.186  0.953  0.084  1.0
  O  O20  1  0.755  0.287  0.387  1.0
  O  O21  1  0.255  0.713  0.613  1.0
  O  O22  1  0.255  0.213  0.887  1.0
  O  O23  1  0.755  0.787  0.113  1.0
  O  O24  1  0.211  0.683  0.018  1.0
  O  O25  1  0.711  0.317  0.982  1.0
  O  O26  1  0.711  0.817  0.518  1.0
  O  O27  1  0.211  0.183  0.482  1.0
[/CIF]
.