Ba7Ga4P9 crystallizes in the orthorhombic Pmmn space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 7-coordinate geometry to one Ga(1), two equivalent P(2), and four equivalent P(1) atoms. In the second Ba site, Ba(2) is bonded in a 8-coordinate geometry to one Ga(1), one P(3), one P(4), one P(5), two equivalent P(1), and two equivalent P(2) atoms. In the third Ba site, Ba(3) is bonded in a 5-coordinate geometry to one P(5) and four equivalent P(1) atoms. There are two inequivalent Ga sites. In the first Ga site, Ga(1) is bonded to one Ba(1), two equivalent Ba(2), one P(2), one P(5), and two equivalent P(1) atoms to form distorted GaBa3P4 tetrahedra that share  a cornercorner with one Ga(1)Ba3P4 tetrahedra and corners with two equivalent Ga(2)P4 tetrahedra. In the second Ga site, Ga(2) is bonded to one P(3), one P(4), and two equivalent P(1) atoms to form distorted GaP4 tetrahedra that share corners with two equivalent Ga(1)Ba3P4 tetrahedra and  an edgeedge with one Ga(2)P4 tetrahedra. There are five inequivalent P sites. In the first P site, P(3) is bonded in a 6-coordinate geometry to four equivalent Ba(2) and two equivalent Ga(2) atoms. In the second P site, P(4) is bonded in a 6-coordinate geometry to four equivalent Ba(2) and two equivalent Ga(2) atoms. In the third P site, P(5) is bonded in a distorted trigonal planar geometry to one Ba(3), four equivalent Ba(2), and two equivalent Ga(1) atoms. In the fourth P site, P(1) is bonded in a 7-coordinate geometry to one Ba(3), two equivalent Ba(1), two equivalent Ba(2), one Ga(1), and one Ga(2) atom. In the fifth P site, P(2) is bonded in a 7-coordinate geometry to two equivalent Ba(1), four equivalent Ba(2), and one Ga(1) atom.
Ba7Ga4P9 crystallizes in the orthorhombic Pmmn space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 7-coordinate geometry to one Ga(1), two equivalent P(2), and four equivalent P(1) atoms. The Ba(1)-Ga(1) bond length is 3.46 Å. There is one shorter (3.29 Å) and one longer (3.67 Å) Ba(1)-P(2) bond length. There are two shorter (3.27 Å) and two longer (3.45 Å) Ba(1)-P(1) bond lengths. In the second Ba site, Ba(2) is bonded in a 8-coordinate geometry to one Ga(1), one P(3), one P(4), one P(5), two equivalent P(1), and two equivalent P(2) atoms. The Ba(2)-Ga(1) bond length is 3.41 Å. The Ba(2)-P(3) bond length is 3.47 Å. The Ba(2)-P(4) bond length is 3.38 Å. The Ba(2)-P(5) bond length is 3.55 Å. There is one shorter (3.42 Å) and one longer (3.49 Å) Ba(2)-P(1) bond length. There is one shorter (3.22 Å) and one longer (3.39 Å) Ba(2)-P(2) bond length. In the third Ba site, Ba(3) is bonded in a 5-coordinate geometry to one P(5) and four equivalent P(1) atoms. The Ba(3)-P(5) bond length is 3.04 Å. All Ba(3)-P(1) bond lengths are 3.16 Å. There are two inequivalent Ga sites. In the first Ga site, Ga(1) is bonded to one Ba(1), two equivalent Ba(2), one P(2), one P(5), and two equivalent P(1) atoms to form distorted GaBa3P4 tetrahedra that share  a cornercorner with one Ga(1)Ba3P4 tetrahedra and corners with two equivalent Ga(2)P4 tetrahedra. The Ga(1)-P(2) bond length is 2.37 Å. The Ga(1)-P(5) bond length is 2.41 Å. Both Ga(1)-P(1) bond lengths are 2.48 Å. In the second Ga site, Ga(2) is bonded to one P(3), one P(4), and two equivalent P(1) atoms to form distorted GaP4 tetrahedra that share corners with two equivalent Ga(1)Ba3P4 tetrahedra and  an edgeedge with one Ga(2)P4 tetrahedra. The Ga(2)-P(3) bond length is 2.48 Å. The Ga(2)-P(4) bond length is 2.47 Å. Both Ga(2)-P(1) bond lengths are 2.43 Å. There are five inequivalent P sites. In the first P site, P(3) is bonded in a 6-coordinate geometry to four equivalent Ba(2) and two equivalent Ga(2) atoms. In the second P site, P(4) is bonded in a 6-coordinate geometry to four equivalent Ba(2) and two equivalent Ga(2) atoms. In the third P site, P(5) is bonded in a distorted trigonal planar geometry to one Ba(3), four equivalent Ba(2), and two equivalent Ga(1) atoms. In the fourth P site, P(1) is bonded in a 7-coordinate geometry to one Ba(3), two equivalent Ba(1), two equivalent Ba(2), one Ga(1), and one Ga(2) atom. In the fifth P site, P(2) is bonded in a 7-coordinate geometry to two equivalent Ba(1), four equivalent Ba(2), and one Ga(1) atom.