K3Gd3(PS4)4 crystallizes in the monoclinic C2/c space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 8-coordinate geometry to one S(1), one S(3), one S(4), one S(5), two equivalent S(6), and two equivalent S(8) atoms. In the second K site, K(2) is bonded in a body-centered cubic geometry to two equivalent S(1), two equivalent S(2), two equivalent S(4), and two equivalent S(5) atoms. There are two inequivalent Gd sites. In the first Gd site, Gd(1) is bonded in a 8-coordinate geometry to one S(1), one S(3), one S(6), one S(8), two equivalent S(2), and two equivalent S(7) atoms. In the second Gd site, Gd(2) is bonded in a 8-coordinate geometry to two equivalent S(3), two equivalent S(4), two equivalent S(5), and two equivalent S(7) atoms. There are two inequivalent P sites. In the first P site, P(1) is bonded in a tetrahedral geometry to one S(1), one S(5), one S(7), and one S(8) atom. In the second P site, P(2) is bonded in a tetrahedral geometry to one S(2), one S(3), one S(4), and one S(6) atom. There are eight inequivalent S sites. In the first S site, S(1) is bonded in a 4-coordinate geometry to one K(1), one K(2), one Gd(1), and one P(1) atom. In the second S site, S(2) is bonded in a distorted rectangular see-saw-like geometry to one K(2), two equivalent Gd(1), and one P(2) atom. In the third S site, S(3) is bonded to one K(1), one Gd(1), one Gd(2), and one P(2) atom to form distorted SKGd2P trigonal pyramids that share  a cornercorner with one S(5)K2GdP trigonal pyramid,  a cornercorner with one S(3)KGd2P trigonal pyramid, and  an edgeedge with one S(5)K2GdP trigonal pyramid. In the fourth S site, S(4) is bonded in a rectangular see-saw-like geometry to one K(1), one K(2), one Gd(2), and one P(2) atom. In the fifth S site, S(5) is bonded to one K(1), one K(2), one Gd(2), and one P(1) atom to form distorted SK2GdP trigonal pyramids that share  a cornercorner with one S(3)KGd2P trigonal pyramid, corners with two equivalent S(5)K2GdP trigonal pyramids, and  an edgeedge with one S(3)KGd2P trigonal pyramid. In the sixth S site, S(6) is bonded in a 4-coordinate geometry to two equivalent K(1), one Gd(1), and one P(2) atom. In the seventh S site, S(7) is bonded in a distorted rectangular see-saw-like geometry to one Gd(2), two equivalent Gd(1), and one P(1) atom. In the eighth S site, S(8) is bonded in a distorted rectangular see-saw-like geometry to two equivalent K(1), one Gd(1), and one P(1) atom.
K3Gd3(PS4)4 crystallizes in the monoclinic C2/c space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 8-coordinate geometry to one S(1), one S(3), one S(4), one S(5), two equivalent S(6), and two equivalent S(8) atoms. The K(1)-S(1) bond length is 3.66 Å. The K(1)-S(3) bond length is 3.30 Å. The K(1)-S(4) bond length is 3.35 Å. The K(1)-S(5) bond length is 3.43 Å. There is one shorter (3.38 Å) and one longer (3.67 Å) K(1)-S(6) bond length. There is one shorter (3.28 Å) and one longer (3.39 Å) K(1)-S(8) bond length. In the second K site, K(2) is bonded in a body-centered cubic geometry to two equivalent S(1), two equivalent S(2), two equivalent S(4), and two equivalent S(5) atoms. Both K(2)-S(1) bond lengths are 3.35 Å. Both K(2)-S(2) bond lengths are 3.43 Å. Both K(2)-S(4) bond lengths are 3.31 Å. Both K(2)-S(5) bond lengths are 3.24 Å. There are two inequivalent Gd sites. In the first Gd site, Gd(1) is bonded in a 8-coordinate geometry to one S(1), one S(3), one S(6), one S(8), two equivalent S(2), and two equivalent S(7) atoms. The Gd(1)-S(1) bond length is 2.82 Å. The Gd(1)-S(3) bond length is 2.86 Å. The Gd(1)-S(6) bond length is 2.82 Å. The Gd(1)-S(8) bond length is 2.80 Å. There is one shorter (2.98 Å) and one longer (3.09 Å) Gd(1)-S(2) bond length. There is one shorter (3.01 Å) and one longer (3.12 Å) Gd(1)-S(7) bond length. In the second Gd site, Gd(2) is bonded in a 8-coordinate geometry to two equivalent S(3), two equivalent S(4), two equivalent S(5), and two equivalent S(7) atoms. Both Gd(2)-S(3) bond lengths are 2.90 Å. Both Gd(2)-S(4) bond lengths are 2.87 Å. Both Gd(2)-S(5) bond lengths are 2.88 Å. Both Gd(2)-S(7) bond lengths are 3.09 Å. There are two inequivalent P sites. In the first P site, P(1) is bonded in a tetrahedral geometry to one S(1), one S(5), one S(7), and one S(8) atom. The P(1)-S(1) bond length is 2.05 Å. The P(1)-S(5) bond length is 2.04 Å. The P(1)-S(7) bond length is 2.09 Å. The P(1)-S(8) bond length is 2.05 Å. In the second P site, P(2) is bonded in a tetrahedral geometry to one S(2), one S(3), one S(4), and one S(6) atom. The P(2)-S(2) bond length is 2.05 Å. The P(2)-S(3) bond length is 2.08 Å. The P(2)-S(4) bond length is 2.05 Å. The P(2)-S(6) bond length is 2.04 Å. There are eight inequivalent S sites. In the first S site, S(1) is bonded in a 4-coordinate geometry to one K(1), one K(2), one Gd(1), and one P(1) atom. In the second S site, S(2) is bonded in a distorted rectangular see-saw-like geometry to one K(2), two equivalent Gd(1), and one P(2) atom. In the third S site, S(3) is bonded to one K(1), one Gd(1), one Gd(2), and one P(2) atom to form distorted SKGd2P trigonal pyramids that share  a cornercorner with one S(5)K2GdP trigonal pyramid,  a cornercorner with one S(3)KGd2P trigonal pyramid, and  an edgeedge with one S(5)K2GdP trigonal pyramid. In the fourth S site, S(4) is bonded in a rectangular see-saw-like geometry to one K(1), one K(2), one Gd(2), and one P(2) atom. In the fifth S site, S(5) is bonded to one K(1), one K(2), one Gd(2), and one P(1) atom to form distorted SK2GdP trigonal pyramids that share  a cornercorner with one S(3)KGd2P trigonal pyramid, corners with two equivalent S(5)K2GdP trigonal pyramids, and  an edgeedge with one S(3)KGd2P trigonal pyramid. In the sixth S site, S(6) is bonded in a 4-coordinate geometry to two equivalent K(1), one Gd(1), and one P(2) atom. In the seventh S site, S(7) is bonded in a distorted rectangular see-saw-like geometry to one Gd(2), two equivalent Gd(1), and one P(1) atom. In the eighth S site, S(8) is bonded in a distorted rectangular see-saw-like geometry to two equivalent K(1), one Gd(1), and one P(1) atom.