The compound described by BaGe4O9 crystallizes in the trigonal P3 space group. Ba(1) is bonded in a 10-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), one O(6), one O(8), one O(9), and two equivalent O(7) atoms. There are six inequivalent Ge sites. In the first Ge site, Ge(1) is bonded to three equivalent O(1) and three equivalent O(6) atoms to form corner-sharing GeO6 octahedra. In the second Ge site, Ge(2) is bonded to three equivalent O(5) and three equivalent O(8) atoms to form corner-sharing GeO6 octahedra. In the third Ge site, Ge(3) is bonded to three equivalent O(2) and three equivalent O(9) atoms to form corner-sharing GeO6 octahedra. In the fourth Ge site, Ge(4) is bonded to one O(1), one O(3), one O(6), and one O(7) atom to form GeO4 tetrahedra that share corners with two equivalent Ge(1)O6 octahedra,  a cornercorner with one Ge(5)O4 tetrahedra, and  a cornercorner with one Ge(6)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 54-60°. In the fifth Ge site, Ge(5) is bonded to one O(2), one O(3), one O(4), and one O(9) atom to form GeO4 tetrahedra that share corners with two equivalent Ge(3)O6 octahedra,  a cornercorner with one Ge(4)O4 tetrahedra, and  a cornercorner with one Ge(6)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 59-61°. In the sixth Ge site, Ge(6) is bonded to one O(4), one O(5), one O(7), and one O(8) atom to form GeO4 tetrahedra that share corners with two equivalent Ge(2)O6 octahedra,  a cornercorner with one Ge(4)O4 tetrahedra, and  a cornercorner with one Ge(5)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 54-60°. There are nine inequivalent O sites. In the first O site, O(7) is bonded in a bent 120 degrees geometry to two equivalent Ba(1), one Ge(4), and one Ge(6) atom. In the second O site, O(8) is bonded in a distorted bent 120 degrees geometry to one Ba(1), one Ge(2), and one Ge(6) atom. In the third O site, O(9) is bonded in a distorted bent 120 degrees geometry to one Ba(1), one Ge(3), and one Ge(5) atom. In the fourth O site, O(1) is bonded in a distorted trigonal planar geometry to one Ba(1), one Ge(1), and one Ge(4) atom. In the fifth O site, O(2) is bonded in a distorted bent 120 degrees geometry to one Ba(1), one Ge(3), and one Ge(5) atom. In the sixth O site, O(3) is bonded in a distorted bent 120 degrees geometry to one Ba(1), one Ge(4), and one Ge(5) atom. In the seventh O site, O(4) is bonded in a distorted bent 120 degrees geometry to one Ba(1), one Ge(5), and one Ge(6) atom. In the eighth O site, O(5) is bonded in a distorted trigonal planar geometry to one Ba(1), one Ge(2), and one Ge(6) atom. In the ninth O site, O(6) is bonded in a bent 120 degrees geometry to one Ba(1), one Ge(1), and one Ge(4) atom. is represented by the CIF file [CIF]
data_BaGe4O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   11.824
_cell_length_b   11.824
_cell_length_c   4.810
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   582.418
_cell_formula_units_Z   3
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
  Ba  Ba0  1  0.331  0.331  1.000  1.0
  Ba  Ba1  1  1.000  0.669  1.000  1.0
  Ba  Ba2  1  0.669  0.000  1.000  1.0
  Ge  Ge3  1  0.333  0.667  0.893  1.0
  Ge  Ge4  1  0.667  0.333  0.104  1.0
  Ge  Ge5  1  0.000  0.000  0.995  1.0
  Ge  Ge6  1  0.338  0.851  0.404  1.0
  Ge  Ge7  1  0.513  0.662  0.404  1.0
  Ge  Ge8  1  0.149  0.487  0.404  1.0
  Ge  Ge9  1  0.181  0.001  0.498  1.0
  Ge  Ge10  1  0.820  0.819  0.498  1.0
  Ge  Ge11  1  0.999  0.180  0.498  1.0
  Ge  Ge12  1  0.487  0.149  0.593  1.0
  Ge  Ge13  1  0.662  0.513  0.593  1.0
  Ge  Ge14  1  0.851  0.338  0.593  1.0
  O  O15  1  0.412  0.819  0.118  1.0
  O  O16  1  0.407  0.588  0.118  1.0
  O  O17  1  0.181  0.593  0.118  1.0
  O  O18  1  0.154  0.086  0.225  1.0
  O  O19  1  0.932  0.846  0.225  1.0
  O  O20  1  0.914  0.068  0.225  1.0
  O  O21  1  0.213  0.888  0.308  1.0
  O  O22  1  0.675  0.787  0.308  1.0
  O  O23  1  0.112  0.325  0.308  1.0
  O  O24  1  0.325  0.113  0.692  1.0
  O  O25  1  0.788  0.675  0.692  1.0
  O  O26  1  0.887  0.212  0.692  1.0
  O  O27  1  0.592  0.181  0.880  1.0
  O  O28  1  0.589  0.408  0.880  1.0
  O  O29  1  0.819  0.411  0.880  1.0
  O  O30  1  0.250  0.736  0.668  1.0
  O  O31  1  0.486  0.750  0.668  1.0
  O  O32  1  0.264  0.514  0.668  1.0
  O  O33  1  0.482  0.001  0.496  1.0
  O  O34  1  0.518  0.518  0.496  1.0
  O  O35  1  0.999  0.482  0.496  1.0
  O  O36  1  0.514  0.264  0.329  1.0
  O  O37  1  0.750  0.486  0.329  1.0
  O  O38  1  0.736  0.250  0.329  1.0
  O  O39  1  0.063  0.911  0.757  1.0
  O  O40  1  0.848  0.937  0.757  1.0
  O  O41  1  0.089  0.152  0.757  1.0
[/CIF]
.
The compound described by BaGe4O9 crystallizes in the trigonal P3 space group. Ba(1) is bonded in a 10-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), one O(6), one O(8), one O(9), and two equivalent O(7) atoms. There are six inequivalent Ge sites. In the first Ge site, Ge(1) is bonded to three equivalent O(1) and three equivalent O(6) atoms to form corner-sharing GeO6 octahedra. In the second Ge site, Ge(2) is bonded to three equivalent O(5) and three equivalent O(8) atoms to form corner-sharing GeO6 octahedra. In the third Ge site, Ge(3) is bonded to three equivalent O(2) and three equivalent O(9) atoms to form corner-sharing GeO6 octahedra. In the fourth Ge site, Ge(4) is bonded to one O(1), one O(3), one O(6), and one O(7) atom to form GeO4 tetrahedra that share corners with two equivalent Ge(1)O6 octahedra,  a cornercorner with one Ge(5)O4 tetrahedra, and  a cornercorner with one Ge(6)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 54-60°. In the fifth Ge site, Ge(5) is bonded to one O(2), one O(3), one O(4), and one O(9) atom to form GeO4 tetrahedra that share corners with two equivalent Ge(3)O6 octahedra,  a cornercorner with one Ge(4)O4 tetrahedra, and  a cornercorner with one Ge(6)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 59-61°. In the sixth Ge site, Ge(6) is bonded to one O(4), one O(5), one O(7), and one O(8) atom to form GeO4 tetrahedra that share corners with two equivalent Ge(2)O6 octahedra,  a cornercorner with one Ge(4)O4 tetrahedra, and  a cornercorner with one Ge(5)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 54-60°. There are nine inequivalent O sites. In the first O site, O(7) is bonded in a bent 120 degrees geometry to two equivalent Ba(1), one Ge(4), and one Ge(6) atom. In the second O site, O(8) is bonded in a distorted bent 120 degrees geometry to one Ba(1), one Ge(2), and one Ge(6) atom. In the third O site, O(9) is bonded in a distorted bent 120 degrees geometry to one Ba(1), one Ge(3), and one Ge(5) atom. In the fourth O site, O(1) is bonded in a distorted trigonal planar geometry to one Ba(1), one Ge(1), and one Ge(4) atom. In the fifth O site, O(2) is bonded in a distorted bent 120 degrees geometry to one Ba(1), one Ge(3), and one Ge(5) atom. In the sixth O site, O(3) is bonded in a distorted bent 120 degrees geometry to one Ba(1), one Ge(4), and one Ge(5) atom. In the seventh O site, O(4) is bonded in a distorted bent 120 degrees geometry to one Ba(1), one Ge(5), and one Ge(6) atom. In the eighth O site, O(5) is bonded in a distorted trigonal planar geometry to one Ba(1), one Ge(2), and one Ge(6) atom. In the ninth O site, O(6) is bonded in a bent 120 degrees geometry to one Ba(1), one Ge(1), and one Ge(4) atom. is represented by the CIF file [CIF]
data_BaGe4O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   11.824
_cell_length_b   11.824
_cell_length_c   4.810
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   582.418
_cell_formula_units_Z   3
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
  Ba  Ba0  1  0.331  0.331  1.000  1.0
  Ba  Ba1  1  1.000  0.669  1.000  1.0
  Ba  Ba2  1  0.669  0.000  1.000  1.0
  Ge  Ge3  1  0.333  0.667  0.893  1.0
  Ge  Ge4  1  0.667  0.333  0.104  1.0
  Ge  Ge5  1  0.000  0.000  0.995  1.0
  Ge  Ge6  1  0.338  0.851  0.404  1.0
  Ge  Ge7  1  0.513  0.662  0.404  1.0
  Ge  Ge8  1  0.149  0.487  0.404  1.0
  Ge  Ge9  1  0.181  0.001  0.498  1.0
  Ge  Ge10  1  0.820  0.819  0.498  1.0
  Ge  Ge11  1  0.999  0.180  0.498  1.0
  Ge  Ge12  1  0.487  0.149  0.593  1.0
  Ge  Ge13  1  0.662  0.513  0.593  1.0
  Ge  Ge14  1  0.851  0.338  0.593  1.0
  O  O15  1  0.412  0.819  0.118  1.0
  O  O16  1  0.407  0.588  0.118  1.0
  O  O17  1  0.181  0.593  0.118  1.0
  O  O18  1  0.154  0.086  0.225  1.0
  O  O19  1  0.932  0.846  0.225  1.0
  O  O20  1  0.914  0.068  0.225  1.0
  O  O21  1  0.213  0.888  0.308  1.0
  O  O22  1  0.675  0.787  0.308  1.0
  O  O23  1  0.112  0.325  0.308  1.0
  O  O24  1  0.325  0.113  0.692  1.0
  O  O25  1  0.788  0.675  0.692  1.0
  O  O26  1  0.887  0.212  0.692  1.0
  O  O27  1  0.592  0.181  0.880  1.0
  O  O28  1  0.589  0.408  0.880  1.0
  O  O29  1  0.819  0.411  0.880  1.0
  O  O30  1  0.250  0.736  0.668  1.0
  O  O31  1  0.486  0.750  0.668  1.0
  O  O32  1  0.264  0.514  0.668  1.0
  O  O33  1  0.482  0.001  0.496  1.0
  O  O34  1  0.518  0.518  0.496  1.0
  O  O35  1  0.999  0.482  0.496  1.0
  O  O36  1  0.514  0.264  0.329  1.0
  O  O37  1  0.750  0.486  0.329  1.0
  O  O38  1  0.736  0.250  0.329  1.0
  O  O39  1  0.063  0.911  0.757  1.0
  O  O40  1  0.848  0.937  0.757  1.0
  O  O41  1  0.089  0.152  0.757  1.0
[/CIF]
.