KTa2PO8 crystallizes in the trigonal R3 space group. K(1) is bonded in a 8-coordinate geometry to one O(1), one O(4), one O(5), one O(8), two equivalent O(3), and two equivalent O(7) atoms. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(1), one O(2), one O(5), one O(6), and two equivalent O(4) atoms to form TaO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with two equivalent Ta(2)O6 octahedra, and corners with two equivalent P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 4-37°. In the second Ta site, Ta(2) is bonded to one O(1), one O(2), one O(3), one O(7), and two equivalent O(8) atoms to form TaO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with two equivalent Ta(2)O6 octahedra, and corners with two equivalent P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 4-38°. P(1) is bonded to one O(3), one O(5), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with two equivalent Ta(1)O6 octahedra and corners with two equivalent Ta(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 35-44°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one K(1), one Ta(1), and one Ta(2) atom. In the second O site, O(2) is bonded in a linear geometry to one Ta(1) and one Ta(2) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to two equivalent K(1), one Ta(2), and one P(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one K(1) and two equivalent Ta(1) atoms. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one K(1), one Ta(1), and one P(1) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Ta(1) and one P(1) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to two equivalent K(1), one Ta(2), and one P(1) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one K(1) and two equivalent Ta(2) atoms.
KTa2PO8 crystallizes in the trigonal R3 space group. K(1) is bonded in a 8-coordinate geometry to one O(1), one O(4), one O(5), one O(8), two equivalent O(3), and two equivalent O(7) atoms. The K(1)-O(1) bond length is 3.35 Å. The K(1)-O(4) bond length is 3.31 Å. The K(1)-O(5) bond length is 2.78 Å. The K(1)-O(8) bond length is 2.73 Å. There is one shorter (3.18 Å) and one longer (3.24 Å) K(1)-O(3) bond length. There is one shorter (2.86 Å) and one longer (3.21 Å) K(1)-O(7) bond length. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(1), one O(2), one O(5), one O(6), and two equivalent O(4) atoms to form TaO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with two equivalent Ta(2)O6 octahedra, and corners with two equivalent P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 4-37°. The Ta(1)-O(1) bond length is 1.95 Å. The Ta(1)-O(2) bond length is 1.93 Å. The Ta(1)-O(5) bond length is 2.08 Å. The Ta(1)-O(6) bond length is 2.06 Å. There is one shorter (1.88 Å) and one longer (2.00 Å) Ta(1)-O(4) bond length. In the second Ta site, Ta(2) is bonded to one O(1), one O(2), one O(3), one O(7), and two equivalent O(8) atoms to form TaO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with two equivalent Ta(2)O6 octahedra, and corners with two equivalent P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 4-38°. The Ta(2)-O(1) bond length is 1.95 Å. The Ta(2)-O(2) bond length is 1.88 Å. The Ta(2)-O(3) bond length is 2.09 Å. The Ta(2)-O(7) bond length is 2.13 Å. There is one shorter (1.89 Å) and one longer (2.00 Å) Ta(2)-O(8) bond length. P(1) is bonded to one O(3), one O(5), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with two equivalent Ta(1)O6 octahedra and corners with two equivalent Ta(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 35-44°. The P(1)-O(3) bond length is 1.53 Å. The P(1)-O(5) bond length is 1.53 Å. The P(1)-O(6) bond length is 1.53 Å. The P(1)-O(7) bond length is 1.53 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one K(1), one Ta(1), and one Ta(2) atom. In the second O site, O(2) is bonded in a linear geometry to one Ta(1) and one Ta(2) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to two equivalent K(1), one Ta(2), and one P(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one K(1) and two equivalent Ta(1) atoms. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one K(1), one Ta(1), and one P(1) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Ta(1) and one P(1) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to two equivalent K(1), one Ta(2), and one P(1) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one K(1) and two equivalent Ta(2) atoms.