Sm2Zr2O7 crystallizes in the orthorhombic Pmma space group. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded in a 6-coordinate geometry to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms. In the second Sm site, Sm(2) is bonded to two equivalent O(4) and four equivalent O(5) atoms to form a mixture of distorted edge and corner-sharing SmO6 octahedra. The corner-sharing octahedral tilt angles are 72°. There are two inequivalent Zr sites. In the first Zr site, Zr(1) is bonded in a body-centered cubic geometry to two equivalent O(1), two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms. In the second Zr site, Zr(2) is bonded in a body-centered cubic geometry to two equivalent O(1), two equivalent O(3), and four equivalent O(2) atoms. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Zr(1) and two equivalent Zr(2) atoms to form OZr4 tetrahedra that share corners with two equivalent O(3)Sm2Zr2 tetrahedra, corners with two equivalent O(4)Sm2Zr2 tetrahedra, corners with four equivalent O(5)Sm3Zr tetrahedra, corners with four equivalent O(2)SmZr3 tetrahedra, corners with four equivalent O(1)Zr4 tetrahedra,  an edgeedge with one O(3)Sm2Zr2 tetrahedra,  an edgeedge with one O(4)Sm2Zr2 tetrahedra, and edges with four equivalent O(2)SmZr3 tetrahedra. In the second O site, O(2) is bonded to one Sm(1), one Zr(1), and two equivalent Zr(2) atoms to form OSmZr3 tetrahedra that share corners with two equivalent O(3)Sm2Zr2 tetrahedra, corners with two equivalent O(4)Sm2Zr2 tetrahedra, corners with two equivalent O(5)Sm3Zr tetrahedra, corners with two equivalent O(1)Zr4 tetrahedra, corners with six equivalent O(2)SmZr3 tetrahedra,  an edgeedge with one O(5)Sm3Zr tetrahedra,  an edgeedge with one O(2)SmZr3 tetrahedra, edges with two equivalent O(3)Sm2Zr2 tetrahedra, and edges with two equivalent O(1)Zr4 tetrahedra. In the third O site, O(3) is bonded to two equivalent Sm(1) and two equivalent Zr(2) atoms to form OSm2Zr2 tetrahedra that share corners with two equivalent O(1)Zr4 tetrahedra, corners with four equivalent O(3)Sm2Zr2 tetrahedra, corners with four equivalent O(5)Sm3Zr tetrahedra, corners with four equivalent O(2)SmZr3 tetrahedra,  an edgeedge with one O(1)Zr4 tetrahedra, and edges with four equivalent O(2)SmZr3 tetrahedra. In the fourth O site, O(4) is bonded to two equivalent Sm(2) and two equivalent Zr(1) atoms to form OSm2Zr2 tetrahedra that share corners with two equivalent O(1)Zr4 tetrahedra, corners with four equivalent O(4)Sm2Zr2 tetrahedra, corners with four equivalent O(5)Sm3Zr tetrahedra, corners with four equivalent O(2)SmZr3 tetrahedra,  an edgeedge with one O(1)Zr4 tetrahedra, and edges with four equivalent O(5)Sm3Zr tetrahedra. In the fifth O site, O(5) is bonded to one Sm(1), two equivalent Sm(2), and one Zr(1) atom to form distorted OSm3Zr tetrahedra that share corners with two equivalent O(3)Sm2Zr2 tetrahedra, corners with two equivalent O(4)Sm2Zr2 tetrahedra, corners with two equivalent O(2)SmZr3 tetrahedra, corners with two equivalent O(1)Zr4 tetrahedra, corners with six equivalent O(5)Sm3Zr tetrahedra,  an edgeedge with one O(5)Sm3Zr tetrahedra,  an edgeedge with one O(2)SmZr3 tetrahedra, and edges with two equivalent O(4)Sm2Zr2 tetrahedra.
Sm2Zr2O7 crystallizes in the orthorhombic Pmma space group. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded in a 6-coordinate geometry to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms. Both Sm(1)-O(2) bond lengths are 2.39 Å. Both Sm(1)-O(3) bond lengths are 2.24 Å. Both Sm(1)-O(5) bond lengths are 2.24 Å. In the second Sm site, Sm(2) is bonded to two equivalent O(4) and four equivalent O(5) atoms to form a mixture of distorted edge and corner-sharing SmO6 octahedra. The corner-sharing octahedral tilt angles are 72°. Both Sm(2)-O(4) bond lengths are 2.35 Å. All Sm(2)-O(5) bond lengths are 2.34 Å. There are two inequivalent Zr sites. In the first Zr site, Zr(1) is bonded in a body-centered cubic geometry to two equivalent O(1), two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms. Both Zr(1)-O(1) bond lengths are 2.17 Å. Both Zr(1)-O(2) bond lengths are 2.20 Å. Both Zr(1)-O(4) bond lengths are 2.32 Å. Both Zr(1)-O(5) bond lengths are 2.60 Å. In the second Zr site, Zr(2) is bonded in a body-centered cubic geometry to two equivalent O(1), two equivalent O(3), and four equivalent O(2) atoms. Both Zr(2)-O(1) bond lengths are 2.39 Å. Both Zr(2)-O(3) bond lengths are 2.22 Å. All Zr(2)-O(2) bond lengths are 2.23 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Zr(1) and two equivalent Zr(2) atoms to form OZr4 tetrahedra that share corners with two equivalent O(3)Sm2Zr2 tetrahedra, corners with two equivalent O(4)Sm2Zr2 tetrahedra, corners with four equivalent O(5)Sm3Zr tetrahedra, corners with four equivalent O(2)SmZr3 tetrahedra, corners with four equivalent O(1)Zr4 tetrahedra,  an edgeedge with one O(3)Sm2Zr2 tetrahedra,  an edgeedge with one O(4)Sm2Zr2 tetrahedra, and edges with four equivalent O(2)SmZr3 tetrahedra. In the second O site, O(2) is bonded to one Sm(1), one Zr(1), and two equivalent Zr(2) atoms to form OSmZr3 tetrahedra that share corners with two equivalent O(3)Sm2Zr2 tetrahedra, corners with two equivalent O(4)Sm2Zr2 tetrahedra, corners with two equivalent O(5)Sm3Zr tetrahedra, corners with two equivalent O(1)Zr4 tetrahedra, corners with six equivalent O(2)SmZr3 tetrahedra,  an edgeedge with one O(5)Sm3Zr tetrahedra,  an edgeedge with one O(2)SmZr3 tetrahedra, edges with two equivalent O(3)Sm2Zr2 tetrahedra, and edges with two equivalent O(1)Zr4 tetrahedra. In the third O site, O(3) is bonded to two equivalent Sm(1) and two equivalent Zr(2) atoms to form OSm2Zr2 tetrahedra that share corners with two equivalent O(1)Zr4 tetrahedra, corners with four equivalent O(3)Sm2Zr2 tetrahedra, corners with four equivalent O(5)Sm3Zr tetrahedra, corners with four equivalent O(2)SmZr3 tetrahedra,  an edgeedge with one O(1)Zr4 tetrahedra, and edges with four equivalent O(2)SmZr3 tetrahedra. In the fourth O site, O(4) is bonded to two equivalent Sm(2) and two equivalent Zr(1) atoms to form OSm2Zr2 tetrahedra that share corners with two equivalent O(1)Zr4 tetrahedra, corners with four equivalent O(4)Sm2Zr2 tetrahedra, corners with four equivalent O(5)Sm3Zr tetrahedra, corners with four equivalent O(2)SmZr3 tetrahedra,  an edgeedge with one O(1)Zr4 tetrahedra, and edges with four equivalent O(5)Sm3Zr tetrahedra. In the fifth O site, O(5) is bonded to one Sm(1), two equivalent Sm(2), and one Zr(1) atom to form distorted OSm3Zr tetrahedra that share corners with two equivalent O(3)Sm2Zr2 tetrahedra, corners with two equivalent O(4)Sm2Zr2 tetrahedra, corners with two equivalent O(2)SmZr3 tetrahedra, corners with two equivalent O(1)Zr4 tetrahedra, corners with six equivalent O(5)Sm3Zr tetrahedra,  an edgeedge with one O(5)Sm3Zr tetrahedra,  an edgeedge with one O(2)SmZr3 tetrahedra, and edges with two equivalent O(4)Sm2Zr2 tetrahedra.