LiK3P2O7 crystallizes in the orthorhombic C222_1 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. In the second K site, K(2) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. Li(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form LiO4 tetrahedra that share corners with four equivalent P(1)O4 tetrahedra. P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra and corners with two equivalent Li(1)O4 tetrahedra. There are four inequivalent O sites. In the first O site, O(3) is bonded in a distorted single-bond geometry to one K(1), two equivalent K(2), and one P(1) atom. In the second O site, O(4) is bonded in a distorted bent 120 degrees geometry to two equivalent P(1) atoms. In the third O site, O(1) is bonded in a 2-coordinate geometry to one K(1), two equivalent K(2), one Li(1), and one P(1) atom. In the fourth O site, O(2) is bonded in a 2-coordinate geometry to one K(1), two equivalent K(2), one Li(1), and one P(1) atom.
LiK3P2O7 crystallizes in the orthorhombic C222_1 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. Both K(1)-O(1) bond lengths are 2.87 Å. Both K(1)-O(2) bond lengths are 2.86 Å. Both K(1)-O(3) bond lengths are 2.84 Å. In the second K site, K(2) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. There is one shorter (2.77 Å) and one longer (2.92 Å) K(2)-O(1) bond length. There is one shorter (2.81 Å) and one longer (2.90 Å) K(2)-O(2) bond length. There is one shorter (2.71 Å) and one longer (2.83 Å) K(2)-O(3) bond length. Li(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form LiO4 tetrahedra that share corners with four equivalent P(1)O4 tetrahedra. Both Li(1)-O(1) bond lengths are 2.01 Å. Both Li(1)-O(2) bond lengths are 2.00 Å. P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra and corners with two equivalent Li(1)O4 tetrahedra. The P(1)-O(1) bond length is 1.54 Å. The P(1)-O(2) bond length is 1.54 Å. The P(1)-O(3) bond length is 1.53 Å. The P(1)-O(4) bond length is 1.65 Å. There are four inequivalent O sites. In the first O site, O(3) is bonded in a distorted single-bond geometry to one K(1), two equivalent K(2), and one P(1) atom. In the second O site, O(4) is bonded in a distorted bent 120 degrees geometry to two equivalent P(1) atoms. In the third O site, O(1) is bonded in a 2-coordinate geometry to one K(1), two equivalent K(2), one Li(1), and one P(1) atom. In the fourth O site, O(2) is bonded in a 2-coordinate geometry to one K(1), two equivalent K(2), one Li(1), and one P(1) atom.