The crystal structure described by PbAl2Si2O8 crystallizes in the triclinic P-1 space group. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1), one O(4), one O(5), and one O(7) atom to form AlO4 tetrahedra that share  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. In the second Al site, Al(2) is bonded to one O(2), one O(4), one O(6), and one O(8) atom to form AlO4 tetrahedra that share  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. Pb(1) is bonded in a 3-coordinate geometry to one O(3), one O(4), and one O(7) atom. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), one O(6), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and corners with two equivalent Al(2)O4 tetrahedra. In the second Si site, Si(2) is bonded to one O(2), one O(3), one O(5), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra, and corners with two equivalent Al(1)O4 tetrahedra. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Al(1) and one Si(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Al(2) and one Si(2) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Pb(1), one Si(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Al(1), one Al(2), and one Pb(1) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one Al(1) and one Si(2) atom. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to one Al(2) and one Si(1) atom. In the seventh O site, O(7) is bonded in a distorted bent 150 degrees geometry to one Al(1), one Pb(1), and one Si(2) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Al(2) and one Si(1) atom. is represented by the CIF card [CIF]
data_Al2Si2PbO8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.279
_cell_length_b   7.808
_cell_length_c   7.869
_cell_angle_alpha   113.830
_cell_angle_beta   103.517
_cell_angle_gamma   103.383
_symmetry_Int_Tables_number   1
_cell_volume   370.147
_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
  Al  Al0  1  0.773  0.818  0.176  1.0
  Al  Al1  1  0.771  0.173  0.814  1.0
  Al  Al2  1  0.227  0.182  0.824  1.0
  Al  Al3  1  0.229  0.827  0.186  1.0
  Si  Si4  1  0.655  0.192  0.424  1.0
  Si  Si5  1  0.655  0.424  0.193  1.0
  Si  Si6  1  0.345  0.808  0.576  1.0
  Si  Si7  1  0.345  0.576  0.807  1.0
  Pb  Pb8  1  0.863  0.719  0.759  1.0
  Pb  Pb9  1  0.137  0.281  0.241  1.0
  O  O10  1  0.775  0.057  0.318  1.0
  O  O11  1  0.775  0.316  0.056  1.0
  O  O12  1  0.225  0.943  0.682  1.0
  O  O13  1  0.225  0.684  0.944  1.0
  O  O14  1  0.705  0.395  0.394  1.0
  O  O15  1  0.295  0.605  0.606  1.0
  O  O16  1  0.997  0.865  0.122  1.0
  O  O17  1  0.003  0.135  0.878  1.0
  O  O18  1  0.741  0.666  0.287  1.0
  O  O19  1  0.744  0.294  0.668  1.0
  O  O20  1  0.259  0.334  0.713  1.0
  O  O21  1  0.256  0.706  0.332  1.0
  O  O22  1  0.592  0.683  0.926  1.0
  O  O23  1  0.591  0.927  0.680  1.0
  O  O24  1  0.408  0.317  0.074  1.0
  O  O25  1  0.409  0.073  0.320  1.0
[/CIF]
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The crystal structure described by PbAl2Si2O8 crystallizes in the triclinic P-1 space group. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1), one O(4), one O(5), and one O(7) atom to form AlO4 tetrahedra that share  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. In the second Al site, Al(2) is bonded to one O(2), one O(4), one O(6), and one O(8) atom to form AlO4 tetrahedra that share  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. Pb(1) is bonded in a 3-coordinate geometry to one O(3), one O(4), and one O(7) atom. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), one O(6), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and corners with two equivalent Al(2)O4 tetrahedra. In the second Si site, Si(2) is bonded to one O(2), one O(3), one O(5), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra, and corners with two equivalent Al(1)O4 tetrahedra. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Al(1) and one Si(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Al(2) and one Si(2) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Pb(1), one Si(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Al(1), one Al(2), and one Pb(1) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one Al(1) and one Si(2) atom. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to one Al(2) and one Si(1) atom. In the seventh O site, O(7) is bonded in a distorted bent 150 degrees geometry to one Al(1), one Pb(1), and one Si(2) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Al(2) and one Si(1) atom. is represented by the CIF card [CIF]
data_Al2Si2PbO8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.279
_cell_length_b   7.808
_cell_length_c   7.869
_cell_angle_alpha   113.830
_cell_angle_beta   103.517
_cell_angle_gamma   103.383
_symmetry_Int_Tables_number   1
_cell_volume   370.147
_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
  Al  Al0  1  0.773  0.818  0.176  1.0
  Al  Al1  1  0.771  0.173  0.814  1.0
  Al  Al2  1  0.227  0.182  0.824  1.0
  Al  Al3  1  0.229  0.827  0.186  1.0
  Si  Si4  1  0.655  0.192  0.424  1.0
  Si  Si5  1  0.655  0.424  0.193  1.0
  Si  Si6  1  0.345  0.808  0.576  1.0
  Si  Si7  1  0.345  0.576  0.807  1.0
  Pb  Pb8  1  0.863  0.719  0.759  1.0
  Pb  Pb9  1  0.137  0.281  0.241  1.0
  O  O10  1  0.775  0.057  0.318  1.0
  O  O11  1  0.775  0.316  0.056  1.0
  O  O12  1  0.225  0.943  0.682  1.0
  O  O13  1  0.225  0.684  0.944  1.0
  O  O14  1  0.705  0.395  0.394  1.0
  O  O15  1  0.295  0.605  0.606  1.0
  O  O16  1  0.997  0.865  0.122  1.0
  O  O17  1  0.003  0.135  0.878  1.0
  O  O18  1  0.741  0.666  0.287  1.0
  O  O19  1  0.744  0.294  0.668  1.0
  O  O20  1  0.259  0.334  0.713  1.0
  O  O21  1  0.256  0.706  0.332  1.0
  O  O22  1  0.592  0.683  0.926  1.0
  O  O23  1  0.591  0.927  0.680  1.0
  O  O24  1  0.408  0.317  0.074  1.0
  O  O25  1  0.409  0.073  0.320  1.0
[/CIF]
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