The crystal structure described by Li2Al2(SiO4)3 crystallizes in the orthorhombic Fdd2 space group. Li(1) is bonded in a 5-coordinate geometry to one O(2), one O(3), one O(4), and two equivalent O(6) atoms. Al(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form AlO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra and corners with three equivalent Si(2)O4 tetrahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to two equivalent O(1) and two equivalent O(5) atoms to form SiO4 tetrahedra that share corners with two equivalent Al(1)O4 tetrahedra and corners with two equivalent Si(2)O4 tetrahedra. In the second Si site, Si(2) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra and corners with three equivalent Al(1)O4 tetrahedra. There are six inequivalent O sites. In the first O site, O(3) is bonded in a trigonal planar geometry to one Li(1), one Al(1), and one Si(2) atom. In the second O site, O(4) is bonded in a distorted trigonal planar geometry to one Li(1), one Al(1), and one Si(2) atom. In the third O site, O(5) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. In the fourth O site, O(6) is bonded in a distorted bent 150 degrees geometry to two equivalent Li(1) atoms. In the fifth O site, O(1) is bonded in a bent 150 degrees geometry to one Al(1) and one Si(1) atom. In the sixth O site, O(2) is bonded in a 3-coordinate geometry to one Li(1), one Al(1), and one Si(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Li2Al2(SiO4)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.629
_cell_length_b   9.691
_cell_length_c   9.371
_cell_angle_alpha   82.968
_cell_angle_beta   49.605
_cell_angle_gamma   47.427
_symmetry_Int_Tables_number   1
_cell_volume   531.445
_cell_formula_units_Z   2
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  0.130  0.469  0.797  1.0
  Li  Li1  1  0.605  0.797  0.469  1.0
  Li  Li2  1  0.453  0.645  0.120  1.0
  Li  Li3  1  0.781  0.120  0.645  1.0
  Al  Al4  1  0.004  0.690  0.556  1.0
  Al  Al5  1  0.751  0.556  0.690  1.0
  Al  Al6  1  0.694  0.499  0.246  1.0
  Al  Al7  1  0.560  0.246  0.499  1.0
  Si  Si8  1  0.257  0.243  0.243  1.0
  Si  Si9  1  0.007  0.993  0.993  1.0
  Si  Si10  1  0.242  0.700  0.553  1.0
  Si  Si11  1  0.506  0.553  0.700  1.0
  Si  Si12  1  0.697  0.744  0.008  1.0
  Si  Si13  1  0.550  0.008  0.744  1.0
  O  O14  1  0.200  0.447  0.312  1.0
  O  O15  1  0.041  0.312  0.447  1.0
  O  O16  1  0.938  0.209  0.050  1.0
  O  O17  1  0.803  0.050  0.209  1.0
  O  O18  1  0.102  0.779  0.515  1.0
  O  O19  1  0.604  0.515  0.779  1.0
  O  O20  1  0.735  0.646  0.148  1.0
  O  O21  1  0.471  0.148  0.646  1.0
  O  O22  1  0.923  0.658  0.784  1.0
  O  O23  1  0.635  0.784  0.658  1.0
  O  O24  1  0.466  0.615  0.327  1.0
  O  O25  1  0.592  0.327  0.615  1.0
  O  O26  1  0.316  0.494  0.586  1.0
  O  O27  1  0.604  0.586  0.494  1.0
  O  O28  1  0.664  0.646  0.934  1.0
  O  O29  1  0.756  0.934  0.646  1.0
  O  O30  1  0.070  0.922  0.777  1.0
  O  O31  1  0.230  0.777  0.922  1.0
  O  O32  1  0.473  0.020  0.180  1.0
  O  O33  1  0.328  0.180  0.020  1.0
  O  O34  1  0.581  0.344  0.968  1.0
  O  O35  1  0.107  0.968  0.344  1.0
  O  O36  1  0.282  0.143  0.669  1.0
  O  O37  1  0.906  0.669  0.143  1.0
[/CIF]
.
The crystal structure described by Li2Al2(SiO4)3 crystallizes in the orthorhombic Fdd2 space group. Li(1) is bonded in a 5-coordinate geometry to one O(2), one O(3), one O(4), and two equivalent O(6) atoms. Al(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form AlO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra and corners with three equivalent Si(2)O4 tetrahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to two equivalent O(1) and two equivalent O(5) atoms to form SiO4 tetrahedra that share corners with two equivalent Al(1)O4 tetrahedra and corners with two equivalent Si(2)O4 tetrahedra. In the second Si site, Si(2) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra and corners with three equivalent Al(1)O4 tetrahedra. There are six inequivalent O sites. In the first O site, O(3) is bonded in a trigonal planar geometry to one Li(1), one Al(1), and one Si(2) atom. In the second O site, O(4) is bonded in a distorted trigonal planar geometry to one Li(1), one Al(1), and one Si(2) atom. In the third O site, O(5) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. In the fourth O site, O(6) is bonded in a distorted bent 150 degrees geometry to two equivalent Li(1) atoms. In the fifth O site, O(1) is bonded in a bent 150 degrees geometry to one Al(1) and one Si(1) atom. In the sixth O site, O(2) is bonded in a 3-coordinate geometry to one Li(1), one Al(1), and one Si(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Li2Al2(SiO4)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.629
_cell_length_b   9.691
_cell_length_c   9.371
_cell_angle_alpha   82.968
_cell_angle_beta   49.605
_cell_angle_gamma   47.427
_symmetry_Int_Tables_number   1
_cell_volume   531.445
_cell_formula_units_Z   2
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  0.130  0.469  0.797  1.0
  Li  Li1  1  0.605  0.797  0.469  1.0
  Li  Li2  1  0.453  0.645  0.120  1.0
  Li  Li3  1  0.781  0.120  0.645  1.0
  Al  Al4  1  0.004  0.690  0.556  1.0
  Al  Al5  1  0.751  0.556  0.690  1.0
  Al  Al6  1  0.694  0.499  0.246  1.0
  Al  Al7  1  0.560  0.246  0.499  1.0
  Si  Si8  1  0.257  0.243  0.243  1.0
  Si  Si9  1  0.007  0.993  0.993  1.0
  Si  Si10  1  0.242  0.700  0.553  1.0
  Si  Si11  1  0.506  0.553  0.700  1.0
  Si  Si12  1  0.697  0.744  0.008  1.0
  Si  Si13  1  0.550  0.008  0.744  1.0
  O  O14  1  0.200  0.447  0.312  1.0
  O  O15  1  0.041  0.312  0.447  1.0
  O  O16  1  0.938  0.209  0.050  1.0
  O  O17  1  0.803  0.050  0.209  1.0
  O  O18  1  0.102  0.779  0.515  1.0
  O  O19  1  0.604  0.515  0.779  1.0
  O  O20  1  0.735  0.646  0.148  1.0
  O  O21  1  0.471  0.148  0.646  1.0
  O  O22  1  0.923  0.658  0.784  1.0
  O  O23  1  0.635  0.784  0.658  1.0
  O  O24  1  0.466  0.615  0.327  1.0
  O  O25  1  0.592  0.327  0.615  1.0
  O  O26  1  0.316  0.494  0.586  1.0
  O  O27  1  0.604  0.586  0.494  1.0
  O  O28  1  0.664  0.646  0.934  1.0
  O  O29  1  0.756  0.934  0.646  1.0
  O  O30  1  0.070  0.922  0.777  1.0
  O  O31  1  0.230  0.777  0.922  1.0
  O  O32  1  0.473  0.020  0.180  1.0
  O  O33  1  0.328  0.180  0.020  1.0
  O  O34  1  0.581  0.344  0.968  1.0
  O  O35  1  0.107  0.968  0.344  1.0
  O  O36  1  0.282  0.143  0.669  1.0
  O  O37  1  0.906  0.669  0.143  1.0
[/CIF]
.