K2Hf2O5 crystallizes in the orthorhombic Pnna space group. K(1) is bonded in a 7-coordinate geometry to one O(2), two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms. Hf(1) is bonded to one O(2), one O(3), one O(4), and three equivalent O(1) atoms to form a mixture of corner, edge, and face-sharing HfO6 octahedra. The corner-sharing octahedral tilt angles range from 13-48°. There are four inequivalent O sites. In the first O site, O(4) is bonded in a distorted linear geometry to four equivalent K(1) and two equivalent Hf(1) atoms. In the second O site, O(1) is bonded in a 4-coordinate geometry to two equivalent K(1) and three equivalent Hf(1) atoms. In the third O site, O(2) is bonded in a tetrahedral geometry to two equivalent K(1) and two equivalent Hf(1) atoms. In the fourth O site, O(3) is bonded in a 6-coordinate geometry to four equivalent K(1) and two equivalent Hf(1) atoms.
K2Hf2O5 crystallizes in the orthorhombic Pnna space group. K(1) is bonded in a 7-coordinate geometry to one O(2), two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms. The K(1)-O(2) bond length is 2.55 Å. There is one shorter (2.68 Å) and one longer (3.19 Å) K(1)-O(1) bond length. There is one shorter (2.70 Å) and one longer (3.01 Å) K(1)-O(3) bond length. There is one shorter (2.99 Å) and one longer (3.03 Å) K(1)-O(4) bond length. Hf(1) is bonded to one O(2), one O(3), one O(4), and three equivalent O(1) atoms to form a mixture of corner, edge, and face-sharing HfO6 octahedra. The corner-sharing octahedral tilt angles range from 13-48°. The Hf(1)-O(2) bond length is 2.00 Å. The Hf(1)-O(3) bond length is 2.07 Å. The Hf(1)-O(4) bond length is 2.02 Å. There are a spread of Hf(1)-O(1) bond distances ranging from 2.07-2.23 Å. There are four inequivalent O sites. In the first O site, O(4) is bonded in a distorted linear geometry to four equivalent K(1) and two equivalent Hf(1) atoms. In the second O site, O(1) is bonded in a 4-coordinate geometry to two equivalent K(1) and three equivalent Hf(1) atoms. In the third O site, O(2) is bonded in a tetrahedral geometry to two equivalent K(1) and two equivalent Hf(1) atoms. In the fourth O site, O(3) is bonded in a 6-coordinate geometry to four equivalent K(1) and two equivalent Hf(1) atoms.