The compound described by Li2FeSiO4 is beta beryllia-derived structured and crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form LiO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Li(2)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra, and  an edgeedge with one Li(2)O4 tetrahedra. In the second Li site, Li(2) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form distorted LiO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra,  an edgeedge with one Li(1)O4 tetrahedra, and  an edgeedge with one Fe(1)O4 tetrahedra. Fe(1) is bonded to one O(2), one O(3), and two equivalent O(4) atoms to form FeO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Li(2)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra, and  an edgeedge with one Li(2)O4 tetrahedra. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with four equivalent Li(1)O4 tetrahedra, corners with four equivalent Li(2)O4 tetrahedra, and corners with four equivalent Fe(1)O4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Li(2), two equivalent Li(1), and one Si(1) atom to form OLi3Si tetrahedra that share corners with two equivalent O(1)Li3Si tetrahedra, corners with two equivalent O(4)LiFe2Si tetrahedra, corners with four equivalent O(2)Li2FeSi tetrahedra, corners with two equivalent O(3)Li2FeSi trigonal pyramids, and  an edgeedge with one O(3)Li2FeSi trigonal pyramid. In the second O site, O(2) is bonded to one Li(1), one Li(2), one Fe(1), and one Si(1) atom to form OLi2FeSi tetrahedra that share corners with four equivalent O(1)Li3Si tetrahedra, corners with four equivalent O(4)LiFe2Si tetrahedra, and corners with four equivalent O(3)Li2FeSi trigonal pyramids. In the third O site, O(3) is bonded to one Li(1), one Li(2), one Fe(1), and one Si(1) atom to form distorted OLi2FeSi trigonal pyramids that share corners with two equivalent O(1)Li3Si tetrahedra, corners with two equivalent O(4)LiFe2Si tetrahedra, corners with four equivalent O(2)Li2FeSi tetrahedra,  an edgeedge with one O(1)Li3Si tetrahedra, and  an edgeedge with one O(4)LiFe2Si tetrahedra. In the fourth O site, O(4) is bonded to one Li(2), two equivalent Fe(1), and one Si(1) atom to form distorted OLiFe2Si tetrahedra that share corners with two equivalent O(1)Li3Si tetrahedra, corners with two equivalent O(4)LiFe2Si tetrahedra, corners with four equivalent O(2)Li2FeSi tetrahedra, corners with two equivalent O(3)Li2FeSi trigonal pyramids, and  an edgeedge with one O(3)Li2FeSi trigonal pyramid. is represented by the CIF file [CIF]
data_Li2FeSiO4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.376
_cell_length_b   5.117
_cell_length_c   10.902
_cell_angle_alpha   90.000
_cell_angle_beta   88.340
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   355.517
_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
  Li  Li0  1  0.005  0.200  0.830  1.0
  Li  Li1  1  0.005  0.300  0.330  1.0
  Li  Li2  1  0.216  0.302  0.571  1.0
  Li  Li3  1  0.216  0.198  0.071  1.0
  Li  Li4  1  0.784  0.802  0.929  1.0
  Li  Li5  1  0.784  0.698  0.429  1.0
  Li  Li6  1  0.995  0.700  0.670  1.0
  Li  Li7  1  0.995  0.800  0.170  1.0
  Fe  Fe8  1  0.506  0.207  0.843  1.0
  Fe  Fe9  1  0.494  0.707  0.657  1.0
  Fe  Fe10  1  0.506  0.293  0.343  1.0
  Fe  Fe11  1  0.494  0.793  0.157  1.0
  Si  Si12  1  0.246  0.699  0.910  1.0
  Si  Si13  1  0.246  0.801  0.410  1.0
  Si  Si14  1  0.754  0.199  0.590  1.0
  Si  Si15  1  0.754  0.301  0.090  1.0
  O  O16  1  0.049  0.814  0.837  1.0
  O  O17  1  0.049  0.686  0.337  1.0
  O  O18  1  0.242  0.375  0.911  1.0
  O  O19  1  0.246  0.693  0.553  1.0
  O  O20  1  0.242  0.125  0.411  1.0
  O  O21  1  0.476  0.790  0.842  1.0
  O  O22  1  0.246  0.807  0.053  1.0
  O  O23  1  0.476  0.710  0.342  1.0
  O  O24  1  0.524  0.290  0.658  1.0
  O  O25  1  0.754  0.193  0.947  1.0
  O  O26  1  0.524  0.210  0.158  1.0
  O  O27  1  0.758  0.875  0.589  1.0
  O  O28  1  0.754  0.307  0.447  1.0
  O  O29  1  0.758  0.625  0.089  1.0
  O  O30  1  0.951  0.314  0.663  1.0
  O  O31  1  0.951  0.186  0.163  1.0
[/CIF]
.
The compound described by Li2FeSiO4 is beta beryllia-derived structured and crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form LiO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Li(2)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra, and  an edgeedge with one Li(2)O4 tetrahedra. In the second Li site, Li(2) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form distorted LiO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra,  an edgeedge with one Li(1)O4 tetrahedra, and  an edgeedge with one Fe(1)O4 tetrahedra. Fe(1) is bonded to one O(2), one O(3), and two equivalent O(4) atoms to form FeO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Li(2)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra, and  an edgeedge with one Li(2)O4 tetrahedra. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with four equivalent Li(1)O4 tetrahedra, corners with four equivalent Li(2)O4 tetrahedra, and corners with four equivalent Fe(1)O4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Li(2), two equivalent Li(1), and one Si(1) atom to form OLi3Si tetrahedra that share corners with two equivalent O(1)Li3Si tetrahedra, corners with two equivalent O(4)LiFe2Si tetrahedra, corners with four equivalent O(2)Li2FeSi tetrahedra, corners with two equivalent O(3)Li2FeSi trigonal pyramids, and  an edgeedge with one O(3)Li2FeSi trigonal pyramid. In the second O site, O(2) is bonded to one Li(1), one Li(2), one Fe(1), and one Si(1) atom to form OLi2FeSi tetrahedra that share corners with four equivalent O(1)Li3Si tetrahedra, corners with four equivalent O(4)LiFe2Si tetrahedra, and corners with four equivalent O(3)Li2FeSi trigonal pyramids. In the third O site, O(3) is bonded to one Li(1), one Li(2), one Fe(1), and one Si(1) atom to form distorted OLi2FeSi trigonal pyramids that share corners with two equivalent O(1)Li3Si tetrahedra, corners with two equivalent O(4)LiFe2Si tetrahedra, corners with four equivalent O(2)Li2FeSi tetrahedra,  an edgeedge with one O(1)Li3Si tetrahedra, and  an edgeedge with one O(4)LiFe2Si tetrahedra. In the fourth O site, O(4) is bonded to one Li(2), two equivalent Fe(1), and one Si(1) atom to form distorted OLiFe2Si tetrahedra that share corners with two equivalent O(1)Li3Si tetrahedra, corners with two equivalent O(4)LiFe2Si tetrahedra, corners with four equivalent O(2)Li2FeSi tetrahedra, corners with two equivalent O(3)Li2FeSi trigonal pyramids, and  an edgeedge with one O(3)Li2FeSi trigonal pyramid. is represented by the CIF file [CIF]
data_Li2FeSiO4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.376
_cell_length_b   5.117
_cell_length_c   10.902
_cell_angle_alpha   90.000
_cell_angle_beta   88.340
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   355.517
_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
  Li  Li0  1  0.005  0.200  0.830  1.0
  Li  Li1  1  0.005  0.300  0.330  1.0
  Li  Li2  1  0.216  0.302  0.571  1.0
  Li  Li3  1  0.216  0.198  0.071  1.0
  Li  Li4  1  0.784  0.802  0.929  1.0
  Li  Li5  1  0.784  0.698  0.429  1.0
  Li  Li6  1  0.995  0.700  0.670  1.0
  Li  Li7  1  0.995  0.800  0.170  1.0
  Fe  Fe8  1  0.506  0.207  0.843  1.0
  Fe  Fe9  1  0.494  0.707  0.657  1.0
  Fe  Fe10  1  0.506  0.293  0.343  1.0
  Fe  Fe11  1  0.494  0.793  0.157  1.0
  Si  Si12  1  0.246  0.699  0.910  1.0
  Si  Si13  1  0.246  0.801  0.410  1.0
  Si  Si14  1  0.754  0.199  0.590  1.0
  Si  Si15  1  0.754  0.301  0.090  1.0
  O  O16  1  0.049  0.814  0.837  1.0
  O  O17  1  0.049  0.686  0.337  1.0
  O  O18  1  0.242  0.375  0.911  1.0
  O  O19  1  0.246  0.693  0.553  1.0
  O  O20  1  0.242  0.125  0.411  1.0
  O  O21  1  0.476  0.790  0.842  1.0
  O  O22  1  0.246  0.807  0.053  1.0
  O  O23  1  0.476  0.710  0.342  1.0
  O  O24  1  0.524  0.290  0.658  1.0
  O  O25  1  0.754  0.193  0.947  1.0
  O  O26  1  0.524  0.210  0.158  1.0
  O  O27  1  0.758  0.875  0.589  1.0
  O  O28  1  0.754  0.307  0.447  1.0
  O  O29  1  0.758  0.625  0.089  1.0
  O  O30  1  0.951  0.314  0.663  1.0
  O  O31  1  0.951  0.186  0.163  1.0
[/CIF]
.