Ba2P2O7 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 9-coordinate geometry to one O(5), two equivalent O(2), two equivalent O(4), and four equivalent O(1) atoms. In the second Ba site, Ba(2) is bonded in a 9-coordinate geometry to one O(2), two equivalent O(1), two equivalent O(5), and four equivalent O(4) atoms. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form corner-sharing PO4 tetrahedra. In the second P site, P(2) is bonded to one O(3), one O(5), and two equivalent O(4) atoms to form corner-sharing PO4 tetrahedra. There are five inequivalent O sites. In the first O site, O(4) is bonded in a distorted single-bond geometry to one Ba(1), two equivalent Ba(2), and one P(2) atom. In the second O site, O(5) is bonded in a distorted single-bond geometry to one Ba(1), two equivalent Ba(2), and one P(2) atom. In the third O site, O(1) is bonded in a distorted single-bond geometry to one Ba(2), two equivalent Ba(1), and one P(1) atom. In the fourth O site, O(2) is bonded in a distorted single-bond geometry to one Ba(2), two equivalent Ba(1), and one P(1) atom. In the fifth O site, O(3) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom.
Ba2P2O7 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 9-coordinate geometry to one O(5), two equivalent O(2), two equivalent O(4), and four equivalent O(1) atoms. The Ba(1)-O(5) bond length is 2.62 Å. Both Ba(1)-O(2) bond lengths are 2.97 Å. Both Ba(1)-O(4) bond lengths are 2.85 Å. There are two shorter (2.78 Å) and two longer (2.96 Å) Ba(1)-O(1) bond lengths. In the second Ba site, Ba(2) is bonded in a 9-coordinate geometry to one O(2), two equivalent O(1), two equivalent O(5), and four equivalent O(4) atoms. The Ba(2)-O(2) bond length is 2.86 Å. Both Ba(2)-O(1) bond lengths are 2.80 Å. Both Ba(2)-O(5) bond lengths are 3.14 Å. There are two shorter (2.80 Å) and two longer (2.88 Å) Ba(2)-O(4) bond lengths. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form corner-sharing PO4 tetrahedra. The P(1)-O(2) bond length is 1.54 Å. The P(1)-O(3) bond length is 1.62 Å. Both P(1)-O(1) bond lengths are 1.54 Å. In the second P site, P(2) is bonded to one O(3), one O(5), and two equivalent O(4) atoms to form corner-sharing PO4 tetrahedra. The P(2)-O(3) bond length is 1.63 Å. The P(2)-O(5) bond length is 1.53 Å. Both P(2)-O(4) bond lengths are 1.54 Å. There are five inequivalent O sites. In the first O site, O(4) is bonded in a distorted single-bond geometry to one Ba(1), two equivalent Ba(2), and one P(2) atom. In the second O site, O(5) is bonded in a distorted single-bond geometry to one Ba(1), two equivalent Ba(2), and one P(2) atom. In the third O site, O(1) is bonded in a distorted single-bond geometry to one Ba(2), two equivalent Ba(1), and one P(1) atom. In the fourth O site, O(2) is bonded in a distorted single-bond geometry to one Ba(2), two equivalent Ba(1), and one P(1) atom. In the fifth O site, O(3) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom.