Na4TiAlSi2PO12 crystallizes in the monoclinic Cc space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded in a 8-coordinate geometry to one O(1), one O(10), one O(11), one O(3), one O(7), one O(9), and two equivalent O(5) atoms. In the second Na site, Na(2) is bonded in a 8-coordinate geometry to one O(1), one O(11), one O(12), one O(3), one O(4), one O(6), one O(8), and one O(9) atom. In the third Na site, Na(3) is bonded in a 8-coordinate geometry to one O(10), one O(12), one O(4), one O(6), one O(7), one O(8), and two equivalent O(2) atoms. In the fourth Na site, Na(4) is bonded in a distorted hexagonal planar geometry to one O(10), one O(11), one O(12), one O(7), one O(8), and one O(9) atom. Ti(1) is bonded to one O(10), one O(11), one O(12), one O(4), one O(5), and one O(6) atom to form TiO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and corners with two equivalent P(1)O4 tetrahedra. Al(1) is bonded to one O(1), one O(2), one O(3), one O(7), one O(8), and one O(9) atom to form AlO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and corners with two equivalent P(1)O4 tetrahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(11), one O(2), one O(5), and one O(8) atom to form SiO4 tetrahedra that share corners with two equivalent Ti(1)O6 octahedra and corners with two equivalent Al(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 30-37°. In the second Si site, Si(2) is bonded to one O(12), one O(3), one O(4), and one O(7) atom to form SiO4 tetrahedra that share corners with two equivalent Ti(1)O6 octahedra and corners with two equivalent Al(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 27-37°. P(1) is bonded to one O(1), one O(10), one O(6), and one O(9) atom to form PO4 tetrahedra that share corners with two equivalent Ti(1)O6 octahedra and corners with two equivalent Al(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 30-36°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to one Na(1), one Na(2), one Al(1), and one P(1) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to two equivalent Na(3), one Al(1), and one Si(1) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Na(1), one Na(2), one Al(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Na(2), one Na(3), one Ti(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to two equivalent Na(1), one Ti(1), and one Si(1) atom. In the sixth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one Na(2), one Na(3), one Ti(1), and one P(1) atom. In the seventh O site, O(7) is bonded to one Na(1), one Na(3), one Na(4), one Al(1), and one Si(2) atom to form distorted ONa3AlSi trigonal bipyramids that share  a cornercorner with one O(12)Na3TiSi trigonal bipyramid, corners with two equivalent O(11)Na3TiSi trigonal bipyramids,  an edgeedge with one O(12)Na3TiSi trigonal bipyramid,  a faceface with one O(9)Na3AlP trigonal bipyramid, and  a faceface with one O(8)Na3AlSi trigonal bipyramid. In the eighth O site, O(8) is bonded to one Na(2), one Na(3), one Na(4), one Al(1), and one Si(1) atom to form distorted ONa3AlSi trigonal bipyramids that share  a cornercorner with one O(11)Na3TiSi trigonal bipyramid, corners with three equivalent O(12)Na3TiSi trigonal bipyramids,  an edgeedge with one O(11)Na3TiSi trigonal bipyramid,  a faceface with one O(9)Na3AlP trigonal bipyramid, and  a faceface with one O(7)Na3AlSi trigonal bipyramid. In the ninth O site, O(9) is bonded to one Na(1), one Na(2), one Na(4), one Al(1), and one P(1) atom to form distorted ONa3AlP trigonal bipyramids that share corners with two equivalent O(12)Na3TiSi trigonal bipyramids, corners with three equivalent O(11)Na3TiSi trigonal bipyramids,  a faceface with one O(7)Na3AlSi trigonal bipyramid, and  a faceface with one O(8)Na3AlSi trigonal bipyramid. In the tenth O site, O(10) is bonded in a 5-coordinate geometry to one Na(1), one Na(3), one Na(4), one Ti(1), and one P(1) atom. In the eleventh O site, O(11) is bonded to one Na(1), one Na(2), one Na(4), one Ti(1), and one Si(1) atom to form distorted ONa3TiSi trigonal bipyramids that share  a cornercorner with one O(8)Na3AlSi trigonal bipyramid, corners with two equivalent O(7)Na3AlSi trigonal bipyramids, corners with three equivalent O(9)Na3AlP trigonal bipyramids,  an edgeedge with one O(8)Na3AlSi trigonal bipyramid, and  a faceface with one O(12)Na3TiSi trigonal bipyramid. In the twelfth O site, O(12) is bonded to one Na(2), one Na(3), one Na(4), one Ti(1), and one Si(2) atom to form distorted ONa3TiSi trigonal bipyramids that share  a cornercorner with one O(7)Na3AlSi trigonal bipyramid, corners with two equivalent O(9)Na3AlP trigonal bipyramids, corners with three equivalent O(8)Na3AlSi trigonal bipyramids,  an edgeedge with one O(7)Na3AlSi trigonal bipyramid, and  a faceface with one O(11)Na3TiSi trigonal bipyramid.
Na4TiAlSi2PO12 crystallizes in the monoclinic Cc space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded in a 8-coordinate geometry to one O(1), one O(10), one O(11), one O(3), one O(7), one O(9), and two equivalent O(5) atoms. The Na(1)-O(1) bond length is 2.64 Å. The Na(1)-O(10) bond length is 2.55 Å. The Na(1)-O(11) bond length is 2.41 Å. The Na(1)-O(3) bond length is 2.86 Å. The Na(1)-O(7) bond length is 2.35 Å. The Na(1)-O(9) bond length is 2.50 Å. There is one shorter (2.63 Å) and one longer (2.84 Å) Na(1)-O(5) bond length. In the second Na site, Na(2) is bonded in a 8-coordinate geometry to one O(1), one O(11), one O(12), one O(3), one O(4), one O(6), one O(8), and one O(9) atom. The Na(2)-O(1) bond length is 2.88 Å. The Na(2)-O(11) bond length is 2.49 Å. The Na(2)-O(12) bond length is 2.42 Å. The Na(2)-O(3) bond length is 2.56 Å. The Na(2)-O(4) bond length is 2.85 Å. The Na(2)-O(6) bond length is 2.69 Å. The Na(2)-O(8) bond length is 2.45 Å. The Na(2)-O(9) bond length is 2.41 Å. In the third Na site, Na(3) is bonded in a 8-coordinate geometry to one O(10), one O(12), one O(4), one O(6), one O(7), one O(8), and two equivalent O(2) atoms. The Na(3)-O(10) bond length is 2.45 Å. The Na(3)-O(12) bond length is 2.48 Å. The Na(3)-O(4) bond length is 2.65 Å. The Na(3)-O(6) bond length is 2.88 Å. The Na(3)-O(7) bond length is 2.51 Å. The Na(3)-O(8) bond length is 2.39 Å. There is one shorter (2.59 Å) and one longer (2.82 Å) Na(3)-O(2) bond length. In the fourth Na site, Na(4) is bonded in a distorted hexagonal planar geometry to one O(10), one O(11), one O(12), one O(7), one O(8), and one O(9) atom. The Na(4)-O(10) bond length is 2.56 Å. The Na(4)-O(11) bond length is 2.50 Å. The Na(4)-O(12) bond length is 2.48 Å. The Na(4)-O(7) bond length is 2.44 Å. The Na(4)-O(8) bond length is 2.44 Å. The Na(4)-O(9) bond length is 2.55 Å. Ti(1) is bonded to one O(10), one O(11), one O(12), one O(4), one O(5), and one O(6) atom to form TiO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and corners with two equivalent P(1)O4 tetrahedra. The Ti(1)-O(10) bond length is 2.08 Å. The Ti(1)-O(11) bond length is 2.02 Å. The Ti(1)-O(12) bond length is 2.02 Å. The Ti(1)-O(4) bond length is 1.87 Å. The Ti(1)-O(5) bond length is 1.89 Å. The Ti(1)-O(6) bond length is 1.97 Å. Al(1) is bonded to one O(1), one O(2), one O(3), one O(7), one O(8), and one O(9) atom to form AlO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and corners with two equivalent P(1)O4 tetrahedra. The Al(1)-O(1) bond length is 2.01 Å. The Al(1)-O(2) bond length is 1.84 Å. The Al(1)-O(3) bond length is 1.87 Å. The Al(1)-O(7) bond length is 1.96 Å. The Al(1)-O(8) bond length is 1.92 Å. The Al(1)-O(9) bond length is 2.13 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(11), one O(2), one O(5), and one O(8) atom to form SiO4 tetrahedra that share corners with two equivalent Ti(1)O6 octahedra and corners with two equivalent Al(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 30-37°. The Si(1)-O(11) bond length is 1.65 Å. The Si(1)-O(2) bond length is 1.62 Å. The Si(1)-O(5) bond length is 1.66 Å. The Si(1)-O(8) bond length is 1.64 Å. In the second Si site, Si(2) is bonded to one O(12), one O(3), one O(4), and one O(7) atom to form SiO4 tetrahedra that share corners with two equivalent Ti(1)O6 octahedra and corners with two equivalent Al(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 27-37°. The Si(2)-O(12) bond length is 1.65 Å. The Si(2)-O(3) bond length is 1.62 Å. The Si(2)-O(4) bond length is 1.66 Å. The Si(2)-O(7) bond length is 1.64 Å. P(1) is bonded to one O(1), one O(10), one O(6), and one O(9) atom to form PO4 tetrahedra that share corners with two equivalent Ti(1)O6 octahedra and corners with two equivalent Al(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 30-36°. The P(1)-O(1) bond length is 1.54 Å. The P(1)-O(10) bond length is 1.56 Å. The P(1)-O(6) bond length is 1.57 Å. The P(1)-O(9) bond length is 1.55 Å. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to one Na(1), one Na(2), one Al(1), and one P(1) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to two equivalent Na(3), one Al(1), and one Si(1) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Na(1), one Na(2), one Al(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Na(2), one Na(3), one Ti(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to two equivalent Na(1), one Ti(1), and one Si(1) atom. In the sixth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one Na(2), one Na(3), one Ti(1), and one P(1) atom. In the seventh O site, O(7) is bonded to one Na(1), one Na(3), one Na(4), one Al(1), and one Si(2) atom to form distorted ONa3AlSi trigonal bipyramids that share  a cornercorner with one O(12)Na3TiSi trigonal bipyramid, corners with two equivalent O(11)Na3TiSi trigonal bipyramids,  an edgeedge with one O(12)Na3TiSi trigonal bipyramid,  a faceface with one O(9)Na3AlP trigonal bipyramid, and  a faceface with one O(8)Na3AlSi trigonal bipyramid. In the eighth O site, O(8) is bonded to one Na(2), one Na(3), one Na(4), one Al(1), and one Si(1) atom to form distorted ONa3AlSi trigonal bipyramids that share  a cornercorner with one O(11)Na3TiSi trigonal bipyramid, corners with three equivalent O(12)Na3TiSi trigonal bipyramids,  an edgeedge with one O(11)Na3TiSi trigonal bipyramid,  a faceface with one O(9)Na3AlP trigonal bipyramid, and  a faceface with one O(7)Na3AlSi trigonal bipyramid. In the ninth O site, O(9) is bonded to one Na(1), one Na(2), one Na(4), one Al(1), and one P(1) atom to form distorted ONa3AlP trigonal bipyramids that share corners with two equivalent O(12)Na3TiSi trigonal bipyramids, corners with three equivalent O(11)Na3TiSi trigonal bipyramids,  a faceface with one O(7)Na3AlSi trigonal bipyramid, and  a faceface with one O(8)Na3AlSi trigonal bipyramid. In the tenth O site, O(10) is bonded in a 5-coordinate geometry to one Na(1), one Na(3), one Na(4), one Ti(1), and one P(1) atom. In the eleventh O site, O(11) is bonded to one Na(1), one Na(2), one Na(4), one Ti(1), and one Si(1) atom to form distorted ONa3TiSi trigonal bipyramids that share  a cornercorner with one O(8)Na3AlSi trigonal bipyramid, corners with two equivalent O(7)Na3AlSi trigonal bipyramids, corners with three equivalent O(9)Na3AlP trigonal bipyramids,  an edgeedge with one O(8)Na3AlSi trigonal bipyramid, and  a faceface with one O(12)Na3TiSi trigonal bipyramid. In the twelfth O site, O(12) is bonded to one Na(2), one Na(3), one Na(4), one Ti(1), and one Si(2) atom to form distorted ONa3TiSi trigonal bipyramids that share  a cornercorner with one O(7)Na3AlSi trigonal bipyramid, corners with two equivalent O(9)Na3AlP trigonal bipyramids, corners with three equivalent O(8)Na3AlSi trigonal bipyramids,  an edgeedge with one O(7)Na3AlSi trigonal bipyramid, and  a faceface with one O(11)Na3TiSi trigonal bipyramid.