Na3Hf2Si2PO12 crystallizes in the monoclinic Cc space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one O(1), one O(11), one O(12), one O(2), one O(5), and one O(6) atom. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to one O(1), one O(10), one O(11), one O(12), one O(2), and one O(9) atom. In the third Na site, Na(3) is bonded in a 7-coordinate geometry to one O(1), one O(12), one O(5), one O(6), one O(8), and two equivalent O(3) atoms. There are two inequivalent Hf sites. In the first Hf site, Hf(1) is bonded to one O(1), one O(11), one O(4), one O(5), one O(8), and one O(9) atom to form HfO6 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. In the second Hf site, Hf(2) is bonded to one O(10), one O(12), one O(2), one O(3), one O(6), and one O(7) atom to form HfO6 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(2), one O(5), one O(7), and one O(9) atom to form SiO4 tetrahedra that share corners with two equivalent Hf(1)O6 octahedra and corners with two equivalent Hf(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 14-43°. In the second Si site, Si(2) is bonded to one O(1), one O(10), one O(6), and one O(8) atom to form SiO4 tetrahedra that share corners with two equivalent Hf(1)O6 octahedra and corners with two equivalent Hf(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 24-40°. P(1) is bonded to one O(11), one O(12), one O(3), and one O(4) atom to form PO4 tetrahedra that share corners with two equivalent Hf(1)O6 octahedra and corners with two equivalent Hf(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 20-38°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Na(1), one Na(2), one Na(3), one Hf(1), and one Si(2) atom. In the second O site, O(2) is bonded to one Na(1), one Na(2), one Hf(2), and one Si(1) atom to form distorted corner-sharing ONa2HfSi trigonal pyramids. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to two equivalent Na(3), one Hf(2), and one P(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Hf(1) and one P(1) atom. In the fifth O site, O(5) is bonded to one Na(1), one Na(3), one Hf(1), and one Si(1) atom to form distorted corner-sharing ONa2HfSi trigonal pyramids. In the sixth O site, O(6) is bonded in a rectangular see-saw-like geometry to one Na(1), one Na(3), one Hf(2), and one Si(2) atom. In the seventh O site, O(7) is bonded in a distorted linear geometry to one Hf(2) and one Si(1) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Na(3), one Hf(1), and one Si(2) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Na(2), one Hf(1), and one Si(1) atom. In the tenth O site, O(10) is bonded in a 3-coordinate geometry to one Na(2), one Hf(2), and one Si(2) atom. In the eleventh O site, O(11) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Na(2), one Hf(1), and one P(1) atom. In the twelfth O site, O(12) is bonded in a 5-coordinate geometry to one Na(1), one Na(2), one Na(3), one Hf(2), and one P(1) atom.
Na3Hf2Si2PO12 crystallizes in the monoclinic Cc space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one O(1), one O(11), one O(12), one O(2), one O(5), and one O(6) atom. The Na(1)-O(1) bond length is 2.62 Å. The Na(1)-O(11) bond length is 2.41 Å. The Na(1)-O(12) bond length is 2.77 Å. The Na(1)-O(2) bond length is 2.40 Å. The Na(1)-O(5) bond length is 2.48 Å. The Na(1)-O(6) bond length is 2.52 Å. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to one O(1), one O(10), one O(11), one O(12), one O(2), and one O(9) atom. The Na(2)-O(1) bond length is 2.43 Å. The Na(2)-O(10) bond length is 2.61 Å. The Na(2)-O(11) bond length is 2.60 Å. The Na(2)-O(12) bond length is 2.68 Å. The Na(2)-O(2) bond length is 2.43 Å. The Na(2)-O(9) bond length is 2.57 Å. In the third Na site, Na(3) is bonded in a 7-coordinate geometry to one O(1), one O(12), one O(5), one O(6), one O(8), and two equivalent O(3) atoms. The Na(3)-O(1) bond length is 2.64 Å. The Na(3)-O(12) bond length is 2.46 Å. The Na(3)-O(5) bond length is 2.53 Å. The Na(3)-O(6) bond length is 2.40 Å. The Na(3)-O(8) bond length is 2.50 Å. There is one shorter (2.93 Å) and one longer (2.94 Å) Na(3)-O(3) bond length. There are two inequivalent Hf sites. In the first Hf site, Hf(1) is bonded to one O(1), one O(11), one O(4), one O(5), one O(8), and one O(9) atom to form HfO6 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 Hf(1)-O(1) bond length is 2.09 Å. The Hf(1)-O(11) bond length is 2.18 Å. The Hf(1)-O(4) bond length is 2.06 Å. The Hf(1)-O(5) bond length is 2.09 Å. The Hf(1)-O(8) bond length is 2.01 Å. The Hf(1)-O(9) bond length is 2.05 Å. In the second Hf site, Hf(2) is bonded to one O(10), one O(12), one O(2), one O(3), one O(6), and one O(7) atom to form HfO6 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 Hf(2)-O(10) bond length is 2.05 Å. The Hf(2)-O(12) bond length is 2.20 Å. The Hf(2)-O(2) bond length is 2.07 Å. The Hf(2)-O(3) bond length is 2.12 Å. The Hf(2)-O(6) bond length is 2.10 Å. The Hf(2)-O(7) bond length is 1.97 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(5), one O(7), and one O(9) atom to form SiO4 tetrahedra that share corners with two equivalent Hf(1)O6 octahedra and corners with two equivalent Hf(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 14-43°. The Si(1)-O(2) bond length is 1.64 Å. The Si(1)-O(5) bond length is 1.63 Å. The Si(1)-O(7) bond length is 1.65 Å. The Si(1)-O(9) bond length is 1.64 Å. In the second Si site, Si(2) is bonded to one O(1), one O(10), one O(6), and one O(8) atom to form SiO4 tetrahedra that share corners with two equivalent Hf(1)O6 octahedra and corners with two equivalent Hf(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 24-40°. The Si(2)-O(1) bond length is 1.66 Å. The Si(2)-O(10) bond length is 1.64 Å. The Si(2)-O(6) bond length is 1.64 Å. The Si(2)-O(8) bond length is 1.65 Å. P(1) is bonded to one O(11), one O(12), one O(3), and one O(4) atom to form PO4 tetrahedra that share corners with two equivalent Hf(1)O6 octahedra and corners with two equivalent Hf(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 20-38°. The P(1)-O(11) bond length is 1.55 Å. The P(1)-O(12) bond length is 1.56 Å. The P(1)-O(3) bond length is 1.55 Å. The P(1)-O(4) bond length is 1.54 Å. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Na(1), one Na(2), one Na(3), one Hf(1), and one Si(2) atom. In the second O site, O(2) is bonded to one Na(1), one Na(2), one Hf(2), and one Si(1) atom to form distorted corner-sharing ONa2HfSi trigonal pyramids. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to two equivalent Na(3), one Hf(2), and one P(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Hf(1) and one P(1) atom. In the fifth O site, O(5) is bonded to one Na(1), one Na(3), one Hf(1), and one Si(1) atom to form distorted corner-sharing ONa2HfSi trigonal pyramids. In the sixth O site, O(6) is bonded in a rectangular see-saw-like geometry to one Na(1), one Na(3), one Hf(2), and one Si(2) atom. In the seventh O site, O(7) is bonded in a distorted linear geometry to one Hf(2) and one Si(1) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Na(3), one Hf(1), and one Si(2) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Na(2), one Hf(1), and one Si(1) atom. In the tenth O site, O(10) is bonded in a 3-coordinate geometry to one Na(2), one Hf(2), and one Si(2) atom. In the eleventh O site, O(11) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Na(2), one Hf(1), and one P(1) atom. In the twelfth O site, O(12) is bonded in a 5-coordinate geometry to one Na(1), one Na(2), one Na(3), one Hf(2), and one P(1) atom.