Eu3GaO6 crystallizes in the orthorhombic Cmc2_1 space group. There are two inequivalent Eu sites. In the first Eu site, Eu(1) is bonded to one O(4), two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form distorted EuO7 pentagonal bipyramids that share  a cornercorner with one Eu(2)O7 pentagonal bipyramid, corners with four equivalent Eu(1)O7 pentagonal bipyramids, corners with three equivalent Ga(1)O4 tetrahedra, edges with two equivalent Eu(1)O7 pentagonal bipyramids, edges with three equivalent Eu(2)O7 pentagonal bipyramids,  an edgeedge with one Ga(1)O4 tetrahedra, and  a faceface with one Eu(1)O7 pentagonal bipyramid. In the second Eu site, Eu(2) is bonded to one O(4), two equivalent O(1), and four equivalent O(2) atoms to form distorted EuO7 pentagonal bipyramids that share corners with two equivalent Eu(1)O7 pentagonal bipyramids,  a cornercorner with one Ga(1)O4 tetrahedra, edges with two equivalent Eu(2)O7 pentagonal bipyramids, edges with six equivalent Eu(1)O7 pentagonal bipyramids, and  an edgeedge with one Ga(1)O4 tetrahedra. Ga(1) is bonded to one O(3), one O(4), and two equivalent O(1) atoms to form GaO4 tetrahedra that share  a cornercorner with one Eu(2)O7 pentagonal bipyramid, corners with six equivalent Eu(1)O7 pentagonal bipyramids,  an edgeedge with one Eu(2)O7 pentagonal bipyramid, and edges with two equivalent Eu(1)O7 pentagonal bipyramids. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Eu(2), two equivalent Eu(1), and one Ga(1) atom to form distorted OEu3Ga trigonal pyramids that share corners with two equivalent O(4)Eu3Ga tetrahedra, corners with six equivalent O(2)Eu4 tetrahedra, corners with two equivalent O(1)Eu3Ga trigonal pyramids,  an edgeedge with one O(4)Eu3Ga tetrahedra,  an edgeedge with one O(2)Eu4 tetrahedra, and  an edgeedge with one O(1)Eu3Ga trigonal pyramid. In the second O site, O(2) is bonded to two equivalent Eu(1) and two equivalent Eu(2) atoms to form OEu4 tetrahedra that share corners with two equivalent O(2)Eu4 tetrahedra, corners with four equivalent O(4)Eu3Ga tetrahedra, corners with six equivalent O(1)Eu3Ga trigonal pyramids, edges with three equivalent O(2)Eu4 tetrahedra, and  an edgeedge with one O(1)Eu3Ga trigonal pyramid. In the third O site, O(3) is bonded in a 5-coordinate geometry to four equivalent Eu(1) and one Ga(1) atom. In the fourth O site, O(4) is bonded to one Eu(2), two equivalent Eu(1), and one Ga(1) atom to form distorted OEu3Ga tetrahedra that share corners with eight equivalent O(2)Eu4 tetrahedra, corners with four equivalent O(1)Eu3Ga trigonal pyramids, and edges with two equivalent O(1)Eu3Ga trigonal pyramids.
Eu3GaO6 crystallizes in the orthorhombic Cmc2_1 space group. There are two inequivalent Eu sites. In the first Eu site, Eu(1) is bonded to one O(4), two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form distorted EuO7 pentagonal bipyramids that share  a cornercorner with one Eu(2)O7 pentagonal bipyramid, corners with four equivalent Eu(1)O7 pentagonal bipyramids, corners with three equivalent Ga(1)O4 tetrahedra, edges with two equivalent Eu(1)O7 pentagonal bipyramids, edges with three equivalent Eu(2)O7 pentagonal bipyramids,  an edgeedge with one Ga(1)O4 tetrahedra, and  a faceface with one Eu(1)O7 pentagonal bipyramid. The Eu(1)-O(4) bond length is 2.43 Å. There is one shorter (2.37 Å) and one longer (2.44 Å) Eu(1)-O(1) bond length. There is one shorter (2.27 Å) and one longer (2.35 Å) Eu(1)-O(2) bond length. There is one shorter (2.62 Å) and one longer (2.66 Å) Eu(1)-O(3) bond length. In the second Eu site, Eu(2) is bonded to one O(4), two equivalent O(1), and four equivalent O(2) atoms to form distorted EuO7 pentagonal bipyramids that share corners with two equivalent Eu(1)O7 pentagonal bipyramids,  a cornercorner with one Ga(1)O4 tetrahedra, edges with two equivalent Eu(2)O7 pentagonal bipyramids, edges with six equivalent Eu(1)O7 pentagonal bipyramids, and  an edgeedge with one Ga(1)O4 tetrahedra. The Eu(2)-O(4) bond length is 2.48 Å. Both Eu(2)-O(1) bond lengths are 2.49 Å. There are two shorter (2.34 Å) and two longer (2.39 Å) Eu(2)-O(2) bond lengths. Ga(1) is bonded to one O(3), one O(4), and two equivalent O(1) atoms to form GaO4 tetrahedra that share  a cornercorner with one Eu(2)O7 pentagonal bipyramid, corners with six equivalent Eu(1)O7 pentagonal bipyramids,  an edgeedge with one Eu(2)O7 pentagonal bipyramid, and edges with two equivalent Eu(1)O7 pentagonal bipyramids. The Ga(1)-O(3) bond length is 1.87 Å. The Ga(1)-O(4) bond length is 1.87 Å. Both Ga(1)-O(1) bond lengths are 1.89 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Eu(2), two equivalent Eu(1), and one Ga(1) atom to form distorted OEu3Ga trigonal pyramids that share corners with two equivalent O(4)Eu3Ga tetrahedra, corners with six equivalent O(2)Eu4 tetrahedra, corners with two equivalent O(1)Eu3Ga trigonal pyramids,  an edgeedge with one O(4)Eu3Ga tetrahedra,  an edgeedge with one O(2)Eu4 tetrahedra, and  an edgeedge with one O(1)Eu3Ga trigonal pyramid. In the second O site, O(2) is bonded to two equivalent Eu(1) and two equivalent Eu(2) atoms to form OEu4 tetrahedra that share corners with two equivalent O(2)Eu4 tetrahedra, corners with four equivalent O(4)Eu3Ga tetrahedra, corners with six equivalent O(1)Eu3Ga trigonal pyramids, edges with three equivalent O(2)Eu4 tetrahedra, and  an edgeedge with one O(1)Eu3Ga trigonal pyramid. In the third O site, O(3) is bonded in a 5-coordinate geometry to four equivalent Eu(1) and one Ga(1) atom. In the fourth O site, O(4) is bonded to one Eu(2), two equivalent Eu(1), and one Ga(1) atom to form distorted OEu3Ga tetrahedra that share corners with eight equivalent O(2)Eu4 tetrahedra, corners with four equivalent O(1)Eu3Ga trigonal pyramids, and edges with two equivalent O(1)Eu3Ga trigonal pyramids.