The compound described by Ca6Al3(Si4N9)2 is Chalcostibite-derived structured and crystallizes in the triclinic P1 space group. There are six inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 5-coordinate geometry to one N(1), one N(12), one N(2), one N(4), one N(5), and one N(9) atom. In the second Ca site, Ca(2) is bonded in a 5-coordinate geometry to one N(10), one N(2), one N(3), one N(6), and one N(7) atom. In the third Ca site, Ca(3) is bonded in a 7-coordinate geometry to one N(1), one N(11), one N(18), one N(3), one N(4), one N(7), and one N(8) atom. In the fourth Ca site, Ca(4) is bonded in a 5-coordinate geometry to one N(13), one N(16), one N(2), one N(5), and one N(6) atom. In the fifth Ca site, Ca(5) is bonded in a 5-coordinate geometry to one N(14), one N(17), one N(3), one N(4), and one N(6) atom. In the sixth Ca site, Ca(6) is bonded in a 6-coordinate geometry to one N(1), one N(15), one N(18), one N(2), one N(4), and one N(5) atom. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded to one N(1), one N(13), one N(17), and one N(8) atom to form AlN4 tetrahedra that share  a cornercorner with one Al(2)N4 tetrahedra,  a cornercorner with one Al(3)N4 tetrahedra,  a cornercorner with one Si(3)N4 tetrahedra,  a cornercorner with one Si(4)N4 tetrahedra,  a cornercorner with one Si(5)N4 tetrahedra,  a cornercorner with one Si(7)N4 tetrahedra, and  a cornercorner with one Si(8)N4 tetrahedra. In the second Al site, Al(2) is bonded to one N(10), one N(17), one N(4), and one N(9) atom to form AlN4 tetrahedra that share  a cornercorner with one Al(1)N4 tetrahedra,  a cornercorner with one Si(1)N4 tetrahedra,  a cornercorner with one Si(4)N4 tetrahedra,  a cornercorner with one Si(5)N4 tetrahedra,  a cornercorner with one Si(6)N4 tetrahedra,  a cornercorner with one Si(7)N4 tetrahedra, and  a cornercorner with one Si(8)N4 tetrahedra. In the third Al site, Al(3) is bonded to one N(12), one N(16), one N(6), and one N(8) atom to form AlN4 tetrahedra that share  a cornercorner with one Al(1)N4 tetrahedra,  a cornercorner with one Si(2)N4 tetrahedra,  a cornercorner with one Si(3)N4 tetrahedra,  a cornercorner with one Si(4)N4 tetrahedra,  a cornercorner with one Si(6)N4 tetrahedra,  a cornercorner with one Si(7)N4 tetrahedra, and  a cornercorner with one Si(8)N4 tetrahedra. There are eight inequivalent Si sites. In the first Si site, Si(1) is bonded to one N(14), one N(18), one N(2), and one N(9) atom to form SiN4 tetrahedra that share  a cornercorner with one Al(2)N4 tetrahedra,  a cornercorner with one Si(3)N4 tetrahedra,  a cornercorner with one Si(4)N4 tetrahedra,  a cornercorner with one Si(5)N4 tetrahedra,  a cornercorner with one Si(6)N4 tetrahedra, and  a cornercorner with one Si(8)N4 tetrahedra. In the second Si site, Si(2) is bonded to one N(15), one N(16), one N(3), and one N(7) atom to form SiN4 tetrahedra that share  a cornercorner with one Al(3)N4 tetrahedra,  a cornercorner with one Si(3)N4 tetrahedra,  a cornercorner with one Si(4)N4 tetrahedra,  a cornercorner with one Si(5)N4 tetrahedra,  a cornercorner with one Si(6)N4 tetrahedra, and  a cornercorner with one Si(7)N4 tetrahedra. In the third Si site, Si(3) is bonded to one N(1), one N(11), one N(14), and one N(16) atom to form SiN4 tetrahedra that share  a cornercorner with one Al(1)N4 tetrahedra,  a cornercorner with one Al(3)N4 tetrahedra,  a cornercorner with one Si(1)N4 tetrahedra,  a cornercorner with one Si(2)N4 tetrahedra,  a cornercorner with one Si(6)N4 tetrahedra, and  a cornercorner with one Si(8)N4 tetrahedra. In the fourth Si site, Si(4) is bonded to one N(12), one N(15), one N(17), and one N(2) atom to form SiN4 tetrahedra that share  a cornercorner with one Al(1)N4 tetrahedra,  a cornercorner with one Al(2)N4 tetrahedra,  a cornercorner with one Al(3)N4 tetrahedra,  a cornercorner with one Si(1)N4 tetrahedra,  a cornercorner with one Si(2)N4 tetrahedra,  a cornercorner with one Si(6)N4 tetrahedra, and  a cornercorner with one Si(7)N4 tetrahedra. In the fifth Si site, Si(5) is bonded to one N(10), one N(13), one N(18), and one N(3) atom to form SiN4 tetrahedra that share  a cornercorner with one Al(1)N4 tetrahedra,  a cornercorner with one Al(2)N4 tetrahedra,  a cornercorner with one Si(1)N4 tetrahedra,  a cornercorner with one Si(2)N4 tetrahedra,  a cornercorner with one Si(7)N4 tetrahedra, and  a cornercorner with one Si(8)N4 tetrahedra. In the sixth Si site, Si(6) is bonded to one N(12), one N(14), one N(4), and one N(7) atom to form SiN4 tetrahedra that share  a cornercorner with one Al(2)N4 tetrahedra,  a cornercorner with one Al(3)N4 tetrahedra,  a cornercorner with one Si(1)N4 tetrahedra,  a cornercorner with one Si(2)N4 tetrahedra,  a cornercorner with one Si(3)N4 tetrahedra, and  a cornercorner with one Si(4)N4 tetrahedra. In the seventh Si site, Si(7) is bonded to one N(10), one N(15), one N(5), and one N(8) atom to form SiN4 tetrahedra that share  a cornercorner with one Al(1)N4 tetrahedra,  a cornercorner with one Al(2)N4 tetrahedra,  a cornercorner with one Al(3)N4 tetrahedra,  a cornercorner with one Si(2)N4 tetrahedra,  a cornercorner with one Si(4)N4 tetrahedra, and  a cornercorner with one Si(5)N4 tetrahedra. In the eighth Si site, Si(8) is bonded to one N(11), one N(13), one N(6), and one N(9) atom to form SiN4 tetrahedra that share  a cornercorner with one Al(1)N4 tetrahedra,  a cornercorner with one Al(2)N4 tetrahedra,  a cornercorner with one Al(3)N4 tetrahedra,  a cornercorner with one Si(1)N4 tetrahedra,  a cornercorner with one Si(3)N4 tetrahedra, and  a cornercorner with one Si(5)N4 tetrahedra. There are eighteen inequivalent N sites. In the first N site, N(1) is bonded in a 5-coordinate geometry to one Ca(1), one Ca(3), one Ca(6), one Al(1), and one Si(3) atom. In the second N site, N(2) is bonded in a 6-coordinate geometry to one Ca(1), one Ca(2), one Ca(4), one Ca(6), one Si(1), and one Si(4) atom. In the third N site, N(3) is bonded in a 5-coordinate geometry to one Ca(2), one Ca(3), one Ca(5), one Si(2), and one Si(5) atom. In the fourth N site, N(4) is bonded in a 6-coordinate geometry to one Ca(1), one Ca(3), one Ca(5), one Ca(6), one Al(2), and one Si(6) atom. In the fifth N site, N(5) is bonded in a distorted see-saw-like geometry to one Ca(1), one Ca(4), one Ca(6), and one Si(7) atom. In the sixth N site, N(6) is bonded to one Ca(2), one Ca(4), one Ca(5), one Al(3), and one Si(8) atom to form distorted NCa3AlSi trigonal bipyramids that share  a cornercorner with one N(8)CaAl2Si tetrahedra,  a cornercorner with one N(17)CaAl2Si trigonal pyramid,  a cornercorner with one N(10)CaAlSi2 trigonal pyramid,  a cornercorner with one N(12)CaAlSi2 trigonal pyramid,  a cornercorner with one N(9)CaAlSi2 trigonal pyramid,  a cornercorner with one N(14)CaSi3 trigonal pyramid,  an edgeedge with one N(13)CaAlSi2 trigonal pyramid, and  an edgeedge with one N(16)CaAlSi2 trigonal pyramid. In the seventh N site, N(7) is bonded in a 4-coordinate geometry to one Ca(2), one Ca(3), one Si(2), and one Si(6) atom. In the eighth N site, N(8) is bonded to one Ca(3), one Al(1), one Al(3), and one Si(7) atom to form distorted NCaAl2Si tetrahedra that share  a cornercorner with one N(6)Ca3AlSi trigonal bipyramid,  a cornercorner with one N(17)CaAl2Si trigonal pyramid,  a cornercorner with one N(10)CaAlSi2 trigonal pyramid,  a cornercorner with one N(12)CaAlSi2 trigonal pyramid,  a cornercorner with one N(13)CaAlSi2 trigonal pyramid,  a cornercorner with one N(16)CaAlSi2 trigonal pyramid, and  a cornercorner with one N(15)CaSi3 trigonal pyramid. In the ninth N site, N(9) is bonded to one Ca(1), one Al(2), one Si(1), and one Si(8) atom to form NCaAlSi2 trigonal pyramids that share  a cornercorner with one N(6)Ca3AlSi trigonal bipyramid,  a cornercorner with one N(17)CaAl2Si trigonal pyramid,  a cornercorner with one N(10)CaAlSi2 trigonal pyramid,  a cornercorner with one N(12)CaAlSi2 trigonal pyramid,  a cornercorner with one N(13)CaAlSi2 trigonal pyramid, and  a cornercorner with one N(14)CaSi3 trigonal pyramid. In the tenth N site, N(10) is bonded to one Ca(2), one Al(2), one Si(5), and one Si(7) atom to form distorted NCaAlSi2 trigonal pyramids that share  a cornercorner with one N(8)CaAl2Si tetrahedra,  a cornercorner with one N(6)Ca3AlSi trigonal bipyramid,  a cornercorner with one N(17)CaAl2Si trigonal pyramid,  a cornercorner with one N(13)CaAlSi2 trigonal pyramid,  a cornercorner with one N(9)CaAlSi2 trigonal pyramid, and  a cornercorner with one N(15)CaSi3 trigonal pyramid. In the eleventh N site, N(11) is bonded in a distorted trigonal non-coplanar geometry to one Ca(3), one Si(3), and one Si(8) atom. In the twelfth N site, N(12) is bonded to one Ca(1), one Al(3), one Si(4), and one Si(6) atom to form NCaAlSi2 trigonal pyramids that share  a cornercorner with one N(8)CaAl2Si tetrahedra,  a cornercorner with one N(6)Ca3AlSi trigonal bipyramid,  a cornercorner with one N(17)CaAl2Si trigonal pyramid,  a cornercorner with one N(16)CaAlSi2 trigonal pyramid,  a cornercorner with one N(9)CaAlSi2 trigonal pyramid,  a cornercorner with one N(14)CaSi3 trigonal pyramid, and  a cornercorner with one N(15)CaSi3 trigonal pyramid. In the thirteenth N site, N(13) is bonded to one Ca(4), one Al(1), one Si(5), and one Si(8) atom to form distorted NCaAlSi2 trigonal pyramids that share  a cornercorner with one N(8)CaAl2Si tetrahedra,  a cornercorner with one N(17)CaAl2Si trigonal pyramid,  a cornercorner with one N(10)CaAlSi2 trigonal pyramid,  a cornercorner with one N(16)CaAlSi2 trigonal pyramid,  a cornercorner with one N(9)CaAlSi2 trigonal pyramid, and  an edgeedge with one N(6)Ca3AlSi trigonal bipyramid. In the fourteenth N site, N(14) is bonded to one Ca(5), one Si(1), one Si(3), and one Si(6) atom to form distorted NCaSi3 trigonal pyramids that share  a cornercorner with one N(6)Ca3AlSi trigonal bipyramid,  a cornercorner with one N(17)CaAl2Si trigonal pyramid,  a cornercorner with one N(12)CaAlSi2 trigonal pyramid,  a cornercorner with one N(16)CaAlSi2 trigonal pyramid, and  a cornercorner with one N(9)CaAlSi2 trigonal pyramid. In the fifteenth N site, N(15) is bonded to one Ca(6), one Si(2), one Si(4), and one Si(7) atom to form distorted NCaSi3 trigonal pyramids that share  a cornercorner with one N(8)CaAl2Si tetrahedra,  a cornercorner with one N(17)CaAl2Si trigonal pyramid,  a cornercorner with one N(10)CaAlSi2 trigonal pyramid,  a cornercorner with one N(12)CaAlSi2 trigonal pyramid, and  a cornercorner with one N(16)CaAlSi2 trigonal pyramid. In the sixteenth N site, N(16) is bonded to one Ca(4), one Al(3), one Si(2), and one Si(3) atom to form NCaAlSi2 trigonal pyramids that share  a cornercorner with one N(8)CaAl2Si tetrahedra,  a cornercorner with one N(12)CaAlSi2 trigonal pyramid,  a cornercorner with one N(13)CaAlSi2 trigonal pyramid,  a cornercorner with one N(14)CaSi3 trigonal pyramid,  a cornercorner with one N(15)CaSi3 trigonal pyramid, and  an edgeedge with one N(6)Ca3AlSi trigonal bipyramid. In the seventeenth N site, N(17) is bonded to one Ca(5), one Al(1), one Al(2), and one Si(4) atom to form distorted NCaAl2Si trigonal pyramids that share  a cornercorner with one N(8)CaAl2Si tetrahedra,  a cornercorner with one N(6)Ca3AlSi trigonal bipyramid,  a cornercorner with one N(10)CaAlSi2 trigonal pyramid,  a cornercorner with one N(12)CaAlSi2 trigonal pyramid,  a cornercorner with one N(13)CaAlSi2 trigonal pyramid,  a cornercorner with one N(9)CaAlSi2 trigonal pyramid,  a cornercorner with one N(14)CaSi3 trigonal pyramid, and  a cornercorner with one N(15)CaSi3 trigonal pyramid. In the eighteenth N site, N(18) is bonded in a 3-coordinate geometry to one Ca(3), one Ca(6), one Si(1), and one Si(5) atom. is represented by the CIF file [CIF]
data_Ca6Al3(Si4N9)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.586
_cell_length_b   7.589
_cell_length_c   7.646
_cell_angle_alpha   81.108
_cell_angle_beta   79.605
_cell_angle_gamma   80.139
_symmetry_Int_Tables_number   1
_cell_volume   423.101
_cell_formula_units_Z   1
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
  Ca  Ca0  1  0.567  0.560  0.861  1.0
  Ca  Ca1  1  0.255  0.223  0.523  1.0
  Ca  Ca2  1  0.824  0.933  0.236  1.0
  Ca  Ca3  1  0.279  0.267  0.955  1.0
  Ca  Ca4  1  0.937  0.939  0.623  1.0
  Ca  Ca5  1  0.595  0.553  0.277  1.0
  Al  Al6  1  0.956  0.614  0.953  1.0
  Al  Al7  1  0.907  0.546  0.570  1.0
  Al  Al8  1  0.224  0.891  0.909  1.0
  Si  Si9  1  0.641  0.273  0.609  1.0
  Si  Si10  1  0.306  0.940  0.280  1.0
  Si  Si11  1  0.610  0.961  0.942  1.0
  Si  Si12  1  0.285  0.626  0.610  1.0
  Si  Si13  1  0.957  0.285  0.281  1.0
  Si  Si14  1  0.543  0.889  0.570  1.0
  Si  Si15  1  0.195  0.587  0.233  1.0
  Si  Si16  1  0.889  0.227  0.898  1.0
  N  N17  1  0.726  0.746  0.983  1.0
  N  N18  1  0.431  0.419  0.631  1.0
  N  N19  1  0.094  0.076  0.319  1.0
  N  N20  1  0.739  0.744  0.515  1.0
  N  N21  1  0.379  0.467  0.117  1.0
  N  N22  1  0.089  0.098  0.812  1.0
  N  N23  1  0.463  0.000  0.384  1.0
  N  N24  1  0.092  0.730  0.071  1.0
  N  N25  1  0.795  0.357  0.715  1.0
  N  N26  1  0.046  0.451  0.367  1.0
  N  N27  1  0.714  0.116  0.004  1.0
  N  N28  1  0.368  0.782  0.711  1.0
  N  N29  1  0.945  0.366  0.049  1.0
  N  N30  1  0.594  0.048  0.705  1.0
  N  N31  1  0.275  0.711  0.377  1.0
  N  N32  1  0.383  0.955  0.047  1.0
  N  N33  1  0.064  0.611  0.710  1.0
  N  N34  1  0.744  0.263  0.393  1.0
[/CIF]
.
The compound described by Ca6Al3(Si4N9)2 is Chalcostibite-derived structured and crystallizes in the triclinic P1 space group. There are six inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 5-coordinate geometry to one N(1), one N(12), one N(2), one N(4), one N(5), and one N(9) atom. In the second Ca site, Ca(2) is bonded in a 5-coordinate geometry to one N(10), one N(2), one N(3), one N(6), and one N(7) atom. In the third Ca site, Ca(3) is bonded in a 7-coordinate geometry to one N(1), one N(11), one N(18), one N(3), one N(4), one N(7), and one N(8) atom. In the fourth Ca site, Ca(4) is bonded in a 5-coordinate geometry to one N(13), one N(16), one N(2), one N(5), and one N(6) atom. In the fifth Ca site, Ca(5) is bonded in a 5-coordinate geometry to one N(14), one N(17), one N(3), one N(4), and one N(6) atom. In the sixth Ca site, Ca(6) is bonded in a 6-coordinate geometry to one N(1), one N(15), one N(18), one N(2), one N(4), and one N(5) atom. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded to one N(1), one N(13), one N(17), and one N(8) atom to form AlN4 tetrahedra that share  a cornercorner with one Al(2)N4 tetrahedra,  a cornercorner with one Al(3)N4 tetrahedra,  a cornercorner with one Si(3)N4 tetrahedra,  a cornercorner with one Si(4)N4 tetrahedra,  a cornercorner with one Si(5)N4 tetrahedra,  a cornercorner with one Si(7)N4 tetrahedra, and  a cornercorner with one Si(8)N4 tetrahedra. In the second Al site, Al(2) is bonded to one N(10), one N(17), one N(4), and one N(9) atom to form AlN4 tetrahedra that share  a cornercorner with one Al(1)N4 tetrahedra,  a cornercorner with one Si(1)N4 tetrahedra,  a cornercorner with one Si(4)N4 tetrahedra,  a cornercorner with one Si(5)N4 tetrahedra,  a cornercorner with one Si(6)N4 tetrahedra,  a cornercorner with one Si(7)N4 tetrahedra, and  a cornercorner with one Si(8)N4 tetrahedra. In the third Al site, Al(3) is bonded to one N(12), one N(16), one N(6), and one N(8) atom to form AlN4 tetrahedra that share  a cornercorner with one Al(1)N4 tetrahedra,  a cornercorner with one Si(2)N4 tetrahedra,  a cornercorner with one Si(3)N4 tetrahedra,  a cornercorner with one Si(4)N4 tetrahedra,  a cornercorner with one Si(6)N4 tetrahedra,  a cornercorner with one Si(7)N4 tetrahedra, and  a cornercorner with one Si(8)N4 tetrahedra. There are eight inequivalent Si sites. In the first Si site, Si(1) is bonded to one N(14), one N(18), one N(2), and one N(9) atom to form SiN4 tetrahedra that share  a cornercorner with one Al(2)N4 tetrahedra,  a cornercorner with one Si(3)N4 tetrahedra,  a cornercorner with one Si(4)N4 tetrahedra,  a cornercorner with one Si(5)N4 tetrahedra,  a cornercorner with one Si(6)N4 tetrahedra, and  a cornercorner with one Si(8)N4 tetrahedra. In the second Si site, Si(2) is bonded to one N(15), one N(16), one N(3), and one N(7) atom to form SiN4 tetrahedra that share  a cornercorner with one Al(3)N4 tetrahedra,  a cornercorner with one Si(3)N4 tetrahedra,  a cornercorner with one Si(4)N4 tetrahedra,  a cornercorner with one Si(5)N4 tetrahedra,  a cornercorner with one Si(6)N4 tetrahedra, and  a cornercorner with one Si(7)N4 tetrahedra. In the third Si site, Si(3) is bonded to one N(1), one N(11), one N(14), and one N(16) atom to form SiN4 tetrahedra that share  a cornercorner with one Al(1)N4 tetrahedra,  a cornercorner with one Al(3)N4 tetrahedra,  a cornercorner with one Si(1)N4 tetrahedra,  a cornercorner with one Si(2)N4 tetrahedra,  a cornercorner with one Si(6)N4 tetrahedra, and  a cornercorner with one Si(8)N4 tetrahedra. In the fourth Si site, Si(4) is bonded to one N(12), one N(15), one N(17), and one N(2) atom to form SiN4 tetrahedra that share  a cornercorner with one Al(1)N4 tetrahedra,  a cornercorner with one Al(2)N4 tetrahedra,  a cornercorner with one Al(3)N4 tetrahedra,  a cornercorner with one Si(1)N4 tetrahedra,  a cornercorner with one Si(2)N4 tetrahedra,  a cornercorner with one Si(6)N4 tetrahedra, and  a cornercorner with one Si(7)N4 tetrahedra. In the fifth Si site, Si(5) is bonded to one N(10), one N(13), one N(18), and one N(3) atom to form SiN4 tetrahedra that share  a cornercorner with one Al(1)N4 tetrahedra,  a cornercorner with one Al(2)N4 tetrahedra,  a cornercorner with one Si(1)N4 tetrahedra,  a cornercorner with one Si(2)N4 tetrahedra,  a cornercorner with one Si(7)N4 tetrahedra, and  a cornercorner with one Si(8)N4 tetrahedra. In the sixth Si site, Si(6) is bonded to one N(12), one N(14), one N(4), and one N(7) atom to form SiN4 tetrahedra that share  a cornercorner with one Al(2)N4 tetrahedra,  a cornercorner with one Al(3)N4 tetrahedra,  a cornercorner with one Si(1)N4 tetrahedra,  a cornercorner with one Si(2)N4 tetrahedra,  a cornercorner with one Si(3)N4 tetrahedra, and  a cornercorner with one Si(4)N4 tetrahedra. In the seventh Si site, Si(7) is bonded to one N(10), one N(15), one N(5), and one N(8) atom to form SiN4 tetrahedra that share  a cornercorner with one Al(1)N4 tetrahedra,  a cornercorner with one Al(2)N4 tetrahedra,  a cornercorner with one Al(3)N4 tetrahedra,  a cornercorner with one Si(2)N4 tetrahedra,  a cornercorner with one Si(4)N4 tetrahedra, and  a cornercorner with one Si(5)N4 tetrahedra. In the eighth Si site, Si(8) is bonded to one N(11), one N(13), one N(6), and one N(9) atom to form SiN4 tetrahedra that share  a cornercorner with one Al(1)N4 tetrahedra,  a cornercorner with one Al(2)N4 tetrahedra,  a cornercorner with one Al(3)N4 tetrahedra,  a cornercorner with one Si(1)N4 tetrahedra,  a cornercorner with one Si(3)N4 tetrahedra, and  a cornercorner with one Si(5)N4 tetrahedra. There are eighteen inequivalent N sites. In the first N site, N(1) is bonded in a 5-coordinate geometry to one Ca(1), one Ca(3), one Ca(6), one Al(1), and one Si(3) atom. In the second N site, N(2) is bonded in a 6-coordinate geometry to one Ca(1), one Ca(2), one Ca(4), one Ca(6), one Si(1), and one Si(4) atom. In the third N site, N(3) is bonded in a 5-coordinate geometry to one Ca(2), one Ca(3), one Ca(5), one Si(2), and one Si(5) atom. In the fourth N site, N(4) is bonded in a 6-coordinate geometry to one Ca(1), one Ca(3), one Ca(5), one Ca(6), one Al(2), and one Si(6) atom. In the fifth N site, N(5) is bonded in a distorted see-saw-like geometry to one Ca(1), one Ca(4), one Ca(6), and one Si(7) atom. In the sixth N site, N(6) is bonded to one Ca(2), one Ca(4), one Ca(5), one Al(3), and one Si(8) atom to form distorted NCa3AlSi trigonal bipyramids that share  a cornercorner with one N(8)CaAl2Si tetrahedra,  a cornercorner with one N(17)CaAl2Si trigonal pyramid,  a cornercorner with one N(10)CaAlSi2 trigonal pyramid,  a cornercorner with one N(12)CaAlSi2 trigonal pyramid,  a cornercorner with one N(9)CaAlSi2 trigonal pyramid,  a cornercorner with one N(14)CaSi3 trigonal pyramid,  an edgeedge with one N(13)CaAlSi2 trigonal pyramid, and  an edgeedge with one N(16)CaAlSi2 trigonal pyramid. In the seventh N site, N(7) is bonded in a 4-coordinate geometry to one Ca(2), one Ca(3), one Si(2), and one Si(6) atom. In the eighth N site, N(8) is bonded to one Ca(3), one Al(1), one Al(3), and one Si(7) atom to form distorted NCaAl2Si tetrahedra that share  a cornercorner with one N(6)Ca3AlSi trigonal bipyramid,  a cornercorner with one N(17)CaAl2Si trigonal pyramid,  a cornercorner with one N(10)CaAlSi2 trigonal pyramid,  a cornercorner with one N(12)CaAlSi2 trigonal pyramid,  a cornercorner with one N(13)CaAlSi2 trigonal pyramid,  a cornercorner with one N(16)CaAlSi2 trigonal pyramid, and  a cornercorner with one N(15)CaSi3 trigonal pyramid. In the ninth N site, N(9) is bonded to one Ca(1), one Al(2), one Si(1), and one Si(8) atom to form NCaAlSi2 trigonal pyramids that share  a cornercorner with one N(6)Ca3AlSi trigonal bipyramid,  a cornercorner with one N(17)CaAl2Si trigonal pyramid,  a cornercorner with one N(10)CaAlSi2 trigonal pyramid,  a cornercorner with one N(12)CaAlSi2 trigonal pyramid,  a cornercorner with one N(13)CaAlSi2 trigonal pyramid, and  a cornercorner with one N(14)CaSi3 trigonal pyramid. In the tenth N site, N(10) is bonded to one Ca(2), one Al(2), one Si(5), and one Si(7) atom to form distorted NCaAlSi2 trigonal pyramids that share  a cornercorner with one N(8)CaAl2Si tetrahedra,  a cornercorner with one N(6)Ca3AlSi trigonal bipyramid,  a cornercorner with one N(17)CaAl2Si trigonal pyramid,  a cornercorner with one N(13)CaAlSi2 trigonal pyramid,  a cornercorner with one N(9)CaAlSi2 trigonal pyramid, and  a cornercorner with one N(15)CaSi3 trigonal pyramid. In the eleventh N site, N(11) is bonded in a distorted trigonal non-coplanar geometry to one Ca(3), one Si(3), and one Si(8) atom. In the twelfth N site, N(12) is bonded to one Ca(1), one Al(3), one Si(4), and one Si(6) atom to form NCaAlSi2 trigonal pyramids that share  a cornercorner with one N(8)CaAl2Si tetrahedra,  a cornercorner with one N(6)Ca3AlSi trigonal bipyramid,  a cornercorner with one N(17)CaAl2Si trigonal pyramid,  a cornercorner with one N(16)CaAlSi2 trigonal pyramid,  a cornercorner with one N(9)CaAlSi2 trigonal pyramid,  a cornercorner with one N(14)CaSi3 trigonal pyramid, and  a cornercorner with one N(15)CaSi3 trigonal pyramid. In the thirteenth N site, N(13) is bonded to one Ca(4), one Al(1), one Si(5), and one Si(8) atom to form distorted NCaAlSi2 trigonal pyramids that share  a cornercorner with one N(8)CaAl2Si tetrahedra,  a cornercorner with one N(17)CaAl2Si trigonal pyramid,  a cornercorner with one N(10)CaAlSi2 trigonal pyramid,  a cornercorner with one N(16)CaAlSi2 trigonal pyramid,  a cornercorner with one N(9)CaAlSi2 trigonal pyramid, and  an edgeedge with one N(6)Ca3AlSi trigonal bipyramid. In the fourteenth N site, N(14) is bonded to one Ca(5), one Si(1), one Si(3), and one Si(6) atom to form distorted NCaSi3 trigonal pyramids that share  a cornercorner with one N(6)Ca3AlSi trigonal bipyramid,  a cornercorner with one N(17)CaAl2Si trigonal pyramid,  a cornercorner with one N(12)CaAlSi2 trigonal pyramid,  a cornercorner with one N(16)CaAlSi2 trigonal pyramid, and  a cornercorner with one N(9)CaAlSi2 trigonal pyramid. In the fifteenth N site, N(15) is bonded to one Ca(6), one Si(2), one Si(4), and one Si(7) atom to form distorted NCaSi3 trigonal pyramids that share  a cornercorner with one N(8)CaAl2Si tetrahedra,  a cornercorner with one N(17)CaAl2Si trigonal pyramid,  a cornercorner with one N(10)CaAlSi2 trigonal pyramid,  a cornercorner with one N(12)CaAlSi2 trigonal pyramid, and  a cornercorner with one N(16)CaAlSi2 trigonal pyramid. In the sixteenth N site, N(16) is bonded to one Ca(4), one Al(3), one Si(2), and one Si(3) atom to form NCaAlSi2 trigonal pyramids that share  a cornercorner with one N(8)CaAl2Si tetrahedra,  a cornercorner with one N(12)CaAlSi2 trigonal pyramid,  a cornercorner with one N(13)CaAlSi2 trigonal pyramid,  a cornercorner with one N(14)CaSi3 trigonal pyramid,  a cornercorner with one N(15)CaSi3 trigonal pyramid, and  an edgeedge with one N(6)Ca3AlSi trigonal bipyramid. In the seventeenth N site, N(17) is bonded to one Ca(5), one Al(1), one Al(2), and one Si(4) atom to form distorted NCaAl2Si trigonal pyramids that share  a cornercorner with one N(8)CaAl2Si tetrahedra,  a cornercorner with one N(6)Ca3AlSi trigonal bipyramid,  a cornercorner with one N(10)CaAlSi2 trigonal pyramid,  a cornercorner with one N(12)CaAlSi2 trigonal pyramid,  a cornercorner with one N(13)CaAlSi2 trigonal pyramid,  a cornercorner with one N(9)CaAlSi2 trigonal pyramid,  a cornercorner with one N(14)CaSi3 trigonal pyramid, and  a cornercorner with one N(15)CaSi3 trigonal pyramid. In the eighteenth N site, N(18) is bonded in a 3-coordinate geometry to one Ca(3), one Ca(6), one Si(1), and one Si(5) atom. is represented by the CIF file [CIF]
data_Ca6Al3(Si4N9)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.586
_cell_length_b   7.589
_cell_length_c   7.646
_cell_angle_alpha   81.108
_cell_angle_beta   79.605
_cell_angle_gamma   80.139
_symmetry_Int_Tables_number   1
_cell_volume   423.101
_cell_formula_units_Z   1
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
  Ca  Ca0  1  0.567  0.560  0.861  1.0
  Ca  Ca1  1  0.255  0.223  0.523  1.0
  Ca  Ca2  1  0.824  0.933  0.236  1.0
  Ca  Ca3  1  0.279  0.267  0.955  1.0
  Ca  Ca4  1  0.937  0.939  0.623  1.0
  Ca  Ca5  1  0.595  0.553  0.277  1.0
  Al  Al6  1  0.956  0.614  0.953  1.0
  Al  Al7  1  0.907  0.546  0.570  1.0
  Al  Al8  1  0.224  0.891  0.909  1.0
  Si  Si9  1  0.641  0.273  0.609  1.0
  Si  Si10  1  0.306  0.940  0.280  1.0
  Si  Si11  1  0.610  0.961  0.942  1.0
  Si  Si12  1  0.285  0.626  0.610  1.0
  Si  Si13  1  0.957  0.285  0.281  1.0
  Si  Si14  1  0.543  0.889  0.570  1.0
  Si  Si15  1  0.195  0.587  0.233  1.0
  Si  Si16  1  0.889  0.227  0.898  1.0
  N  N17  1  0.726  0.746  0.983  1.0
  N  N18  1  0.431  0.419  0.631  1.0
  N  N19  1  0.094  0.076  0.319  1.0
  N  N20  1  0.739  0.744  0.515  1.0
  N  N21  1  0.379  0.467  0.117  1.0
  N  N22  1  0.089  0.098  0.812  1.0
  N  N23  1  0.463  0.000  0.384  1.0
  N  N24  1  0.092  0.730  0.071  1.0
  N  N25  1  0.795  0.357  0.715  1.0
  N  N26  1  0.046  0.451  0.367  1.0
  N  N27  1  0.714  0.116  0.004  1.0
  N  N28  1  0.368  0.782  0.711  1.0
  N  N29  1  0.945  0.366  0.049  1.0
  N  N30  1  0.594  0.048  0.705  1.0
  N  N31  1  0.275  0.711  0.377  1.0
  N  N32  1  0.383  0.955  0.047  1.0
  N  N33  1  0.064  0.611  0.710  1.0
  N  N34  1  0.744  0.263  0.393  1.0
[/CIF]
.