K2PO4 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 9-coordinate geometry to one O(3), two equivalent O(4), three equivalent O(1), and three equivalent O(2) atoms. In the second K site, K(2) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. P(1) is bonded in a tetrahedral geometry to one O(1), one O(2), one O(3), and one O(4) atom. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to two equivalent K(2), three equivalent K(1), and one P(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to two equivalent K(2), three equivalent K(1), and one P(1) atom. In the third 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 fourth O site, O(4) is bonded in a distorted single-bond geometry to two equivalent K(1), two equivalent K(2), and one P(1) atom.
K2PO4 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 9-coordinate geometry to one O(3), two equivalent O(4), three equivalent O(1), and three equivalent O(2) atoms. The K(1)-O(3) bond length is 2.77 Å. There is one shorter (2.95 Å) and one longer (3.20 Å) K(1)-O(4) bond length. There are a spread of K(1)-O(1) bond distances ranging from 2.98-3.18 Å. There are a spread of K(1)-O(2) bond distances ranging from 2.86-3.16 Å. In the second K site, K(2) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. There is one shorter (2.70 Å) and one longer (2.89 Å) K(2)-O(1) bond length. There is one shorter (2.73 Å) and one longer (2.86 Å) K(2)-O(2) bond length. There is one shorter (2.94 Å) and one longer (2.98 Å) K(2)-O(3) bond length. There is one shorter (2.73 Å) and one longer (2.91 Å) K(2)-O(4) bond length. P(1) is bonded in a tetrahedral geometry to one O(1), one O(2), one O(3), and one O(4) atom. The P(1)-O(1) bond length is 1.53 Å. The P(1)-O(2) bond length is 1.53 Å. The P(1)-O(3) bond length is 1.70 Å. The P(1)-O(4) bond length is 1.53 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to two equivalent K(2), three equivalent K(1), and one P(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to two equivalent K(2), three equivalent K(1), and one P(1) atom. In the third 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 fourth O site, O(4) is bonded in a distorted single-bond geometry to two equivalent K(1), two equivalent K(2), and one P(1) atom.