The compound described by SrCaAl2(SiN3)2 crystallizes in the triclinic P1 space group. Sr(1) is bonded in a 5-coordinate geometry to one N(2), one N(3), one N(4), and two equivalent N(1) atoms. Ca(1) is bonded in a 5-coordinate geometry to one N(1), one N(5), one N(6), and two equivalent N(2) atoms. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one N(1), one N(3), one N(5), and one N(6) atom to form AlN4 tetrahedra that share corners with two equivalent Al(2)N4 tetrahedra, corners with two equivalent Si(2)N4 tetrahedra, and corners with three equivalent Si(1)N4 tetrahedra. In the second Al site, Al(2) is bonded to one N(2), one N(3), one N(4), and one N(5) atom to form AlN4 tetrahedra that share corners with two equivalent Al(1)N4 tetrahedra, corners with two equivalent Si(1)N4 tetrahedra, and corners with three equivalent Si(2)N4 tetrahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one N(1), one N(4), one N(5), and one N(6) atom to form SiN4 tetrahedra that share corners with two equivalent Al(2)N4 tetrahedra, corners with two equivalent Si(2)N4 tetrahedra, and corners with three equivalent Al(1)N4 tetrahedra. In the second Si site, Si(2) is bonded to one N(2), one N(3), one N(4), and one N(6) atom to form SiN4 tetrahedra that share corners with two equivalent Al(1)N4 tetrahedra, corners with two equivalent Si(1)N4 tetrahedra, and corners with three equivalent Al(2)N4 tetrahedra. There are six inequivalent N sites. In the first N site, N(1) is bonded in a 5-coordinate geometry to two equivalent Sr(1), one Ca(1), one Al(1), and one Si(1) atom. In the second N site, N(2) is bonded in a 2-coordinate geometry to one Sr(1), two equivalent Ca(1), one Al(2), and one Si(2) atom. In the third N site, N(3) is bonded to one Sr(1), one Al(1), one Al(2), and one Si(2) atom to form distorted NSrAl2Si trigonal pyramids that share corners with two equivalent N(5)CaAl2Si trigonal pyramids, corners with two equivalent N(6)CaAlSi2 trigonal pyramids, and corners with three equivalent N(4)SrAlSi2 trigonal pyramids. In the fourth N site, N(4) is bonded to one Sr(1), one Al(2), one Si(1), and one Si(2) atom to form distorted NSrAlSi2 trigonal pyramids that share corners with two equivalent N(5)CaAl2Si trigonal pyramids, corners with two equivalent N(6)CaAlSi2 trigonal pyramids, and corners with three equivalent N(3)SrAl2Si trigonal pyramids. In the fifth N site, N(5) is bonded to one Ca(1), one Al(1), one Al(2), and one Si(1) atom to form NCaAl2Si trigonal pyramids that share corners with two equivalent N(3)SrAl2Si trigonal pyramids, corners with two equivalent N(4)SrAlSi2 trigonal pyramids, and corners with three equivalent N(6)CaAlSi2 trigonal pyramids. In the sixth N site, N(6) is bonded to one Ca(1), one Al(1), one Si(1), and one Si(2) atom to form distorted NCaAlSi2 trigonal pyramids that share corners with two equivalent N(3)SrAl2Si trigonal pyramids, corners with two equivalent N(4)SrAlSi2 trigonal pyramids, and corners with three equivalent N(5)CaAl2Si trigonal pyramids. is represented by the CIF card [CIF]
data_SrCaAl2(SiN3)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.145
_cell_length_b   5.731
_cell_length_c   5.750
_cell_angle_alpha   119.890
_cell_angle_beta   90.135
_cell_angle_gamma   90.138
_symmetry_Int_Tables_number   1
_cell_volume   146.984
_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
  Sr  Sr0  1  0.998  0.679  0.683  1.0
  Ca  Ca1  1  0.495  0.304  0.300  1.0
  Al  Al2  1  0.524  0.022  0.671  1.0
  Al  Al3  1  0.022  0.982  0.330  1.0
  Si  Si4  1  0.520  0.669  0.024  1.0
  Si  Si5  1  0.017  0.333  0.981  1.0
  N  N6  1  0.497  0.755  0.773  1.0
  N  N7  1  0.989  0.233  0.217  1.0
  N  N8  1  0.878  0.113  0.670  1.0
  N  N9  1  0.854  0.645  0.100  1.0
  N  N10  1  0.380  0.907  0.330  1.0
  N  N11  1  0.356  0.358  0.920  1.0
[/CIF]
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The compound described by SrCaAl2(SiN3)2 crystallizes in the triclinic P1 space group. Sr(1) is bonded in a 5-coordinate geometry to one N(2), one N(3), one N(4), and two equivalent N(1) atoms. Ca(1) is bonded in a 5-coordinate geometry to one N(1), one N(5), one N(6), and two equivalent N(2) atoms. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one N(1), one N(3), one N(5), and one N(6) atom to form AlN4 tetrahedra that share corners with two equivalent Al(2)N4 tetrahedra, corners with two equivalent Si(2)N4 tetrahedra, and corners with three equivalent Si(1)N4 tetrahedra. In the second Al site, Al(2) is bonded to one N(2), one N(3), one N(4), and one N(5) atom to form AlN4 tetrahedra that share corners with two equivalent Al(1)N4 tetrahedra, corners with two equivalent Si(1)N4 tetrahedra, and corners with three equivalent Si(2)N4 tetrahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one N(1), one N(4), one N(5), and one N(6) atom to form SiN4 tetrahedra that share corners with two equivalent Al(2)N4 tetrahedra, corners with two equivalent Si(2)N4 tetrahedra, and corners with three equivalent Al(1)N4 tetrahedra. In the second Si site, Si(2) is bonded to one N(2), one N(3), one N(4), and one N(6) atom to form SiN4 tetrahedra that share corners with two equivalent Al(1)N4 tetrahedra, corners with two equivalent Si(1)N4 tetrahedra, and corners with three equivalent Al(2)N4 tetrahedra. There are six inequivalent N sites. In the first N site, N(1) is bonded in a 5-coordinate geometry to two equivalent Sr(1), one Ca(1), one Al(1), and one Si(1) atom. In the second N site, N(2) is bonded in a 2-coordinate geometry to one Sr(1), two equivalent Ca(1), one Al(2), and one Si(2) atom. In the third N site, N(3) is bonded to one Sr(1), one Al(1), one Al(2), and one Si(2) atom to form distorted NSrAl2Si trigonal pyramids that share corners with two equivalent N(5)CaAl2Si trigonal pyramids, corners with two equivalent N(6)CaAlSi2 trigonal pyramids, and corners with three equivalent N(4)SrAlSi2 trigonal pyramids. In the fourth N site, N(4) is bonded to one Sr(1), one Al(2), one Si(1), and one Si(2) atom to form distorted NSrAlSi2 trigonal pyramids that share corners with two equivalent N(5)CaAl2Si trigonal pyramids, corners with two equivalent N(6)CaAlSi2 trigonal pyramids, and corners with three equivalent N(3)SrAl2Si trigonal pyramids. In the fifth N site, N(5) is bonded to one Ca(1), one Al(1), one Al(2), and one Si(1) atom to form NCaAl2Si trigonal pyramids that share corners with two equivalent N(3)SrAl2Si trigonal pyramids, corners with two equivalent N(4)SrAlSi2 trigonal pyramids, and corners with three equivalent N(6)CaAlSi2 trigonal pyramids. In the sixth N site, N(6) is bonded to one Ca(1), one Al(1), one Si(1), and one Si(2) atom to form distorted NCaAlSi2 trigonal pyramids that share corners with two equivalent N(3)SrAl2Si trigonal pyramids, corners with two equivalent N(4)SrAlSi2 trigonal pyramids, and corners with three equivalent N(5)CaAl2Si trigonal pyramids. is represented by the CIF card [CIF]
data_SrCaAl2(SiN3)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.145
_cell_length_b   5.731
_cell_length_c   5.750
_cell_angle_alpha   119.890
_cell_angle_beta   90.135
_cell_angle_gamma   90.138
_symmetry_Int_Tables_number   1
_cell_volume   146.984
_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
  Sr  Sr0  1  0.998  0.679  0.683  1.0
  Ca  Ca1  1  0.495  0.304  0.300  1.0
  Al  Al2  1  0.524  0.022  0.671  1.0
  Al  Al3  1  0.022  0.982  0.330  1.0
  Si  Si4  1  0.520  0.669  0.024  1.0
  Si  Si5  1  0.017  0.333  0.981  1.0
  N  N6  1  0.497  0.755  0.773  1.0
  N  N7  1  0.989  0.233  0.217  1.0
  N  N8  1  0.878  0.113  0.670  1.0
  N  N9  1  0.854  0.645  0.100  1.0
  N  N10  1  0.380  0.907  0.330  1.0
  N  N11  1  0.356  0.358  0.920  1.0
[/CIF]
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