Na4Sc2(PO4)3 crystallizes in the trigonal R-3c space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to two equivalent O(2) and four equivalent O(1) atoms. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to six equivalent O(1) atoms. Sc(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted ScO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra. P(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form PO4 tetrahedra that share corners with four equivalent Sc(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 36-41°. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Na(2), two equivalent Na(1), one Sc(1), and one P(1) atom to form a mixture of distorted edge, face, and corner-sharing ONa3ScP trigonal bipyramids. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Na(1), one Sc(1), and one P(1) atom.
Na4Sc2(PO4)3 crystallizes in the trigonal R-3c space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to two equivalent O(2) and four equivalent O(1) atoms. Both Na(1)-O(2) bond lengths are 2.47 Å. There are two shorter (2.51 Å) and two longer (2.65 Å) Na(1)-O(1) bond lengths. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to six equivalent O(1) atoms. All Na(2)-O(1) bond lengths are 2.46 Å. Sc(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted ScO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra. All Sc(1)-O(1) bond lengths are 2.25 Å. All Sc(1)-O(2) bond lengths are 2.11 Å. P(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form PO4 tetrahedra that share corners with four equivalent Sc(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 36-41°. Both P(1)-O(1) bond lengths are 1.56 Å. Both P(1)-O(2) bond lengths are 1.55 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Na(2), two equivalent Na(1), one Sc(1), and one P(1) atom to form a mixture of distorted edge, face, and corner-sharing ONa3ScP trigonal bipyramids. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Na(1), one Sc(1), and one P(1) atom.