NaMg14CeO16 is Caswellsilverite-derived structured and crystallizes in the orthorhombic Pmmm space group. Na(1) is bonded to two O(2,2); two equivalent O(5); and two equivalent O(8) atoms to form NaO6 octahedra that share corners with two equivalent Na(1)O6 octahedra, corners with two equivalent Mg(2)O6 octahedra, corners with two equivalent Ce(1)O6 octahedra, edges with four equivalent Mg(3)O6 octahedra, edges with four equivalent Mg(6)O6 octahedra, and edges with four equivalent Mg(7)O6 octahedra. The corner-sharing octahedra are not tilted. There are eight inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(1), two equivalent O(6), and two equivalent O(9) atoms to form MgO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra; corners with two equivalent Mg(2)O6 octahedra; corners with two equivalent Ce(1)O6 octahedra; edges with four equivalent Mg(4)O6 octahedra; edges with four Mg(5,5)O6 octahedra; and edges with four equivalent Mg(7)O6 octahedra. The corner-sharing octahedra are not tilted. In the second Mg site, Mg(2) is bonded to two O(2,2); two equivalent O(7); and two equivalent O(9) atoms to form MgO6 octahedra that share corners with two equivalent Na(1)O6 octahedra, corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Mg(2)O6 octahedra, edges with four equivalent Mg(4)O6 octahedra, edges with four equivalent Mg(6)O6 octahedra, and edges with four equivalent Mg(7)O6 octahedra. The corner-sharing octahedra are not tilted. In the third Mg site, Mg(3) is bonded to one O(4), one O(5), two equivalent O(3), and two equivalent O(8) atoms to form MgO6 octahedra that share corners with two equivalent Mg(4)O6 octahedra; corners with four equivalent Mg(3)O6 octahedra; edges with two equivalent Na(1)O6 octahedra; edges with two Mg(5,5)O6 octahedra; edges with two equivalent Mg(6)O6 octahedra; edges with two equivalent Ce(1)O6 octahedra; and edges with four equivalent Mg(7)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-8°. In the fourth Mg site, Mg(4) is bonded to one O(6), one O(7), two equivalent O(3), and two equivalent O(9) atoms to form a mixture of corner and edge-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles range from 0-7°. In the fifth Mg site, Mg(5) is bonded to one O(4), one O(6), two equivalent O(1), and two equivalent O(3) atoms to form MgO6 octahedra that share corners with two equivalent Mg(6)O6 octahedra; corners with four Mg(5,5)O6 octahedra; edges with two equivalent Mg(1)O6 octahedra; edges with two equivalent Mg(3)O6 octahedra; edges with two equivalent Mg(4)O6 octahedra; edges with two equivalent Ce(1)O6 octahedra; and edges with four equivalent Mg(7)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-4°. In the sixth Mg site, Mg(6) is bonded to one O(5), one O(7), two equivalent O(2), and two equivalent O(3) atoms to form MgO6 octahedra that share corners with two equivalent Mg(5)O6 octahedra, corners with four equivalent Mg(6)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, edges with two equivalent Mg(3)O6 octahedra, edges with two equivalent Mg(4)O6 octahedra, and edges with four equivalent Mg(7)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-8°. In the seventh Mg site, Mg(5) is bonded to one O(4), one O(6), two equivalent O(1), and two equivalent O(3) atoms to form MgO6 octahedra that share corners with two equivalent Mg(6)O6 octahedra; corners with four Mg(5,5)O6 octahedra; edges with two equivalent Mg(1)O6 octahedra; edges with two equivalent Mg(3)O6 octahedra; edges with two equivalent Mg(4)O6 octahedra; edges with two equivalent Ce(1)O6 octahedra; and edges with four equivalent Mg(7)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-4°. In the eighth Mg site, Mg(7) is bonded to one O(1), one O(2), one O(8), one O(9), and two equivalent O(3) atoms to form MgO6 octahedra that share corners with six equivalent Mg(7)O6 octahedra,  an edgeedge with one Na(1)O6 octahedra,  an edgeedge with one Mg(1)O6 octahedra,  an edgeedge with one Mg(2)O6 octahedra,  an edgeedge with one Ce(1)O6 octahedra, edges with two equivalent Mg(3)O6 octahedra, edges with two equivalent Mg(4)O6 octahedra, edges with two equivalent Mg(5)O6 octahedra, and edges with two equivalent Mg(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-7°. Ce(1) is bonded to two equivalent O(1), two equivalent O(4), and two equivalent O(8) atoms to form CeO6 octahedra that share corners with two equivalent Na(1)O6 octahedra; corners with two equivalent Mg(1)O6 octahedra; corners with two equivalent Ce(1)O6 octahedra; edges with four equivalent Mg(3)O6 octahedra; edges with four Mg(5,5)O6 octahedra; and edges with four equivalent Mg(7)O6 octahedra. The corner-sharing octahedra are not tilted. There are ten inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), two equivalent Mg(5), two equivalent Mg(7), and one Ce(1) atom to form OCeMg5 octahedra that share corners with two equivalent O(2)NaMg5 octahedra, corners with four equivalent O(1)CeMg5 octahedra, edges with two equivalent O(4)Ce2Mg4 octahedra, edges with two equivalent O(6)Mg6 octahedra, edges with two equivalent O(9)Mg6 octahedra, edges with two equivalent O(8)NaCeMg4 octahedra, and edges with four equivalent O(3)Mg6 octahedra. The corner-sharing octahedral tilt angles range from 0-5°. In the second O site, O(2) is bonded to one Na(1), one Mg(2), two equivalent Mg(6), and two equivalent Mg(7) atoms to form ONaMg5 octahedra that share corners with two equivalent O(1)CeMg5 octahedra; corners with four O(2,2)NaMg5 octahedra; edges with two equivalent O(7)Mg6 octahedra; edges with two equivalent O(9)Mg6 octahedra; edges with two equivalent O(5)Na2Mg4 octahedra; edges with two equivalent O(8)NaCeMg4 octahedra; and edges with four equivalent O(3)Mg6 octahedra. The corner-sharing octahedral tilt angles range from 0-8°. In the third O site, O(2) is bonded to one Na(1), one Mg(2), two equivalent Mg(6), and two equivalent Mg(7) atoms to form ONaMg5 octahedra that share corners with two equivalent O(1)CeMg5 octahedra; corners with four O(2,2)NaMg5 octahedra; edges with two equivalent O(7)Mg6 octahedra; edges with two equivalent O(9)Mg6 octahedra; edges with two equivalent O(5)Na2Mg4 octahedra; edges with two equivalent O(8)NaCeMg4 octahedra; and edges with four equivalent O(3)Mg6 octahedra. The corner-sharing octahedral tilt angles range from 0-8°. In the fourth O site, O(3) is bonded to one Mg(3), one Mg(4), one Mg(5), one Mg(6), and two equivalent Mg(7) atoms to form OMg6 octahedra that share corners with six equivalent O(3)Mg6 octahedra,  an edgeedge with one O(4)Ce2Mg4 octahedra,  an edgeedge with one O(6)Mg6 octahedra,  an edgeedge with one O(7)Mg6 octahedra,  an edgeedge with one O(5)Na2Mg4 octahedra, edges with two equivalent O(1)CeMg5 octahedra, edges with two equivalent O(9)Mg6 octahedra, edges with two equivalent O(8)NaCeMg4 octahedra, and edges with two equivalent O(2)NaMg5 octahedra. The corner-sharing octahedral tilt angles range from 0-11°. In the fifth O site, O(4) is bonded to two equivalent Mg(3); two Mg(5,5); and two equivalent Ce(1) atoms to form OCe2Mg4 octahedra that share corners with two equivalent O(4)Ce2Mg4 octahedra, corners with two equivalent O(6)Mg6 octahedra, corners with two equivalent O(5)Na2Mg4 octahedra, edges with four equivalent O(1)CeMg5 octahedra, edges with four equivalent O(3)Mg6 octahedra, and edges with four equivalent O(8)NaCeMg4 octahedra. The corner-sharing octahedra are not tilted. In the sixth O site, O(5) is bonded to two equivalent Na(1), two equivalent Mg(3), and two equivalent Mg(6) atoms to form ONa2Mg4 octahedra that share corners with two equivalent O(4)Ce2Mg4 octahedra; corners with two equivalent O(7)Mg6 octahedra; corners with two equivalent O(5)Na2Mg4 octahedra; edges with four equivalent O(3)Mg6 octahedra; edges with four equivalent O(8)NaCeMg4 octahedra; and edges with four O(2,2)NaMg5 octahedra. The corner-sharing octahedra are not tilted. In the seventh O site, O(6) is bonded to two equivalent Mg(1); two equivalent Mg(4); and two Mg(5,5) atoms to form OMg6 octahedra that share corners with two equivalent O(4)Ce2Mg4 octahedra, corners with two equivalent O(6)Mg6 octahedra, corners with two equivalent O(7)Mg6 octahedra, edges with four equivalent O(1)CeMg5 octahedra, edges with four equivalent O(3)Mg6 octahedra, and edges with four equivalent O(9)Mg6 octahedra. The corner-sharing octahedra are not tilted. In the eighth O site, O(7) is bonded to two equivalent Mg(2), two equivalent Mg(4), and two equivalent Mg(6) atoms to form OMg6 octahedra that share corners with two equivalent O(6)Mg6 octahedra; corners with two equivalent O(7)Mg6 octahedra; corners with two equivalent O(5)Na2Mg4 octahedra; edges with four equivalent O(3)Mg6 octahedra; edges with four equivalent O(9)Mg6 octahedra; and edges with four O(2,2)NaMg5 octahedra. The corner-sharing octahedra are not tilted. In the ninth O site, O(8) is bonded to one Na(1), two equivalent Mg(3), two equivalent Mg(7), and one Ce(1) atom to form ONaCeMg4 octahedra that share corners with two equivalent O(9)Mg6 octahedra; corners with four equivalent O(8)NaCeMg4 octahedra; edges with two equivalent O(4)Ce2Mg4 octahedra; edges with two equivalent O(1)CeMg5 octahedra; edges with two equivalent O(5)Na2Mg4 octahedra; edges with two O(2,2)NaMg5 octahedra; and edges with four equivalent O(3)Mg6 octahedra. The corner-sharing octahedral tilt angles range from 0-8°. In the tenth O site, O(9) is bonded to one Mg(1), one Mg(2), two equivalent Mg(4), and two equivalent Mg(7) atoms to form OMg6 octahedra that share corners with two equivalent O(8)NaCeMg4 octahedra; corners with four equivalent O(9)Mg6 octahedra; edges with two equivalent O(1)CeMg5 octahedra; edges with two equivalent O(6)Mg6 octahedra; edges with two equivalent O(7)Mg6 octahedra; edges with two O(2,2)NaMg5 octahedra; and edges with four equivalent O(3)Mg6 octahedra. The corner-sharing octahedral tilt angles range from 0-5°.
NaMg14CeO16 is Caswellsilverite-derived structured and crystallizes in the orthorhombic Pmmm space group. Na(1) is bonded to two O(2,2); two equivalent O(5); and two equivalent O(8) atoms to form NaO6 octahedra that share corners with two equivalent Na(1)O6 octahedra, corners with two equivalent Mg(2)O6 octahedra, corners with two equivalent Ce(1)O6 octahedra, edges with four equivalent Mg(3)O6 octahedra, edges with four equivalent Mg(6)O6 octahedra, and edges with four equivalent Mg(7)O6 octahedra. The corner-sharing octahedra are not tilted. Both Na(1)-O(2,2) bond lengths are 2.33 Å. Both Na(1)-O(5) bond lengths are 2.19 Å. Both Na(1)-O(8) bond lengths are 2.16 Å. There are eight inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(1), two equivalent O(6), and two equivalent O(9) atoms to form MgO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra; corners with two equivalent Mg(2)O6 octahedra; corners with two equivalent Ce(1)O6 octahedra; edges with four equivalent Mg(4)O6 octahedra; edges with four Mg(5,5)O6 octahedra; and edges with four equivalent Mg(7)O6 octahedra. The corner-sharing octahedra are not tilted. Both Mg(1)-O(1) bond lengths are 2.03 Å. Both Mg(1)-O(6) bond lengths are 2.19 Å. Both Mg(1)-O(9) bond lengths are 2.19 Å. In the second Mg site, Mg(2) is bonded to two O(2,2); two equivalent O(7); and two equivalent O(9) atoms to form MgO6 octahedra that share corners with two equivalent Na(1)O6 octahedra, corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Mg(2)O6 octahedra, edges with four equivalent Mg(4)O6 octahedra, edges with four equivalent Mg(6)O6 octahedra, and edges with four equivalent Mg(7)O6 octahedra. The corner-sharing octahedra are not tilted. Both Mg(2)-O(2,2) bond lengths are 2.03 Å. Both Mg(2)-O(7) bond lengths are 2.19 Å. Both Mg(2)-O(9) bond lengths are 2.21 Å. In the third Mg site, Mg(3) is bonded to one O(4), one O(5), two equivalent O(3), and two equivalent O(8) atoms to form MgO6 octahedra that share corners with two equivalent Mg(4)O6 octahedra; corners with four equivalent Mg(3)O6 octahedra; edges with two equivalent Na(1)O6 octahedra; edges with two Mg(5,5)O6 octahedra; edges with two equivalent Mg(6)O6 octahedra; edges with two equivalent Ce(1)O6 octahedra; and edges with four equivalent Mg(7)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-8°. The Mg(3)-O(4) bond length is 2.39 Å. The Mg(3)-O(5) bond length is 2.01 Å. Both Mg(3)-O(3) bond lengths are 2.18 Å. Both Mg(3)-O(8) bond lengths are 2.20 Å. In the fourth Mg site, Mg(4) is bonded to one O(6), one O(7), two equivalent O(3), and two equivalent O(9) atoms to form a mixture of corner and edge-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles range from 0-7°. The Mg(4)-O(6) bond length is 2.24 Å. The Mg(4)-O(7) bond length is 2.16 Å. Both Mg(4)-O(3) bond lengths are 2.18 Å. Both Mg(4)-O(9) bond lengths are 2.20 Å. In the fifth Mg site, Mg(5) is bonded to one O(4), one O(6), two equivalent O(1), and two equivalent O(3) atoms to form MgO6 octahedra that share corners with two equivalent Mg(6)O6 octahedra; corners with four Mg(5,5)O6 octahedra; edges with two equivalent Mg(1)O6 octahedra; edges with two equivalent Mg(3)O6 octahedra; edges with two equivalent Mg(4)O6 octahedra; edges with two equivalent Ce(1)O6 octahedra; and edges with four equivalent Mg(7)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-4°. The Mg(5)-O(4) bond length is 2.32 Å. The Mg(5)-O(6) bond length is 2.04 Å. Both Mg(5)-O(1) bond lengths are 2.19 Å. Both Mg(5)-O(3) bond lengths are 2.19 Å. In the sixth Mg site, Mg(6) is bonded to one O(5), one O(7), two equivalent O(2), and two equivalent O(3) atoms to form MgO6 octahedra that share corners with two equivalent Mg(5)O6 octahedra, corners with four equivalent Mg(6)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, edges with two equivalent Mg(3)O6 octahedra, edges with two equivalent Mg(4)O6 octahedra, and edges with four equivalent Mg(7)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-8°. The Mg(6)-O(5) bond length is 2.18 Å. The Mg(6)-O(7) bond length is 2.18 Å. Both Mg(6)-O(2) bond lengths are 2.20 Å. Both Mg(6)-O(3) bond lengths are 2.21 Å. In the seventh Mg site, Mg(5) is bonded to one O(4), one O(6), two equivalent O(1), and two equivalent O(3) atoms to form MgO6 octahedra that share corners with two equivalent Mg(6)O6 octahedra; corners with four Mg(5,5)O6 octahedra; edges with two equivalent Mg(1)O6 octahedra; edges with two equivalent Mg(3)O6 octahedra; edges with two equivalent Mg(4)O6 octahedra; edges with two equivalent Ce(1)O6 octahedra; and edges with four equivalent Mg(7)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-4°. The Mg(5)-O(4) bond length is 2.32 Å. The Mg(5)-O(6) bond length is 2.04 Å. Both Mg(5)-O(1) bond lengths are 2.19 Å. Both Mg(5)-O(3) bond lengths are 2.19 Å. In the eighth Mg site, Mg(7) is bonded to one O(1), one O(2), one O(8), one O(9), and two equivalent O(3) atoms to form MgO6 octahedra that share corners with six equivalent Mg(7)O6 octahedra,  an edgeedge with one Na(1)O6 octahedra,  an edgeedge with one Mg(1)O6 octahedra,  an edgeedge with one Mg(2)O6 octahedra,  an edgeedge with one Ce(1)O6 octahedra, edges with two equivalent Mg(3)O6 octahedra, edges with two equivalent Mg(4)O6 octahedra, edges with two equivalent Mg(5)O6 octahedra, and edges with two equivalent Mg(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-7°. The Mg(7)-O(1) bond length is 2.31 Å. The Mg(7)-O(2) bond length is 2.09 Å. The Mg(7)-O(8) bond length is 2.24 Å. The Mg(7)-O(9) bond length is 2.12 Å. Both Mg(7)-O(3) bond lengths are 2.20 Å. Ce(1) is bonded to two equivalent O(1), two equivalent O(4), and two equivalent O(8) atoms to form CeO6 octahedra that share corners with two equivalent Na(1)O6 octahedra; corners with two equivalent Mg(1)O6 octahedra; corners with two equivalent Ce(1)O6 octahedra; edges with four equivalent Mg(3)O6 octahedra; edges with four Mg(5,5)O6 octahedra; and edges with four equivalent Mg(7)O6 octahedra. The corner-sharing octahedra are not tilted. Both Ce(1)-O(1) bond lengths are 2.33 Å. Both Ce(1)-O(4) bond lengths are 2.19 Å. Both Ce(1)-O(8) bond lengths are 2.24 Å. There are ten inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), two equivalent Mg(5), two equivalent Mg(7), and one Ce(1) atom to form OCeMg5 octahedra that share corners with two equivalent O(2)NaMg5 octahedra, corners with four equivalent O(1)CeMg5 octahedra, edges with two equivalent O(4)Ce2Mg4 octahedra, edges with two equivalent O(6)Mg6 octahedra, edges with two equivalent O(9)Mg6 octahedra, edges with two equivalent O(8)NaCeMg4 octahedra, and edges with four equivalent O(3)Mg6 octahedra. The corner-sharing octahedral tilt angles range from 0-5°. In the second O site, O(2) is bonded to one Na(1), one Mg(2), two equivalent Mg(6), and two equivalent Mg(7) atoms to form ONaMg5 octahedra that share corners with two equivalent O(1)CeMg5 octahedra; corners with four O(2,2)NaMg5 octahedra; edges with two equivalent O(7)Mg6 octahedra; edges with two equivalent O(9)Mg6 octahedra; edges with two equivalent O(5)Na2Mg4 octahedra; edges with two equivalent O(8)NaCeMg4 octahedra; and edges with four equivalent O(3)Mg6 octahedra. The corner-sharing octahedral tilt angles range from 0-8°. In the third O site, O(2) is bonded to one Na(1), one Mg(2), two equivalent Mg(6), and two equivalent Mg(7) atoms to form ONaMg5 octahedra that share corners with two equivalent O(1)CeMg5 octahedra; corners with four O(2,2)NaMg5 octahedra; edges with two equivalent O(7)Mg6 octahedra; edges with two equivalent O(9)Mg6 octahedra; edges with two equivalent O(5)Na2Mg4 octahedra; edges with two equivalent O(8)NaCeMg4 octahedra; and edges with four equivalent O(3)Mg6 octahedra. The corner-sharing octahedral tilt angles range from 0-8°. Both O(2)-Mg(6) bond lengths are 2.20 Å. Both O(2)-Mg(7) bond lengths are 2.09 Å. In the fourth O site, O(3) is bonded to one Mg(3), one Mg(4), one Mg(5), one Mg(6), and two equivalent Mg(7) atoms to form OMg6 octahedra that share corners with six equivalent O(3)Mg6 octahedra,  an edgeedge with one O(4)Ce2Mg4 octahedra,  an edgeedge with one O(6)Mg6 octahedra,  an edgeedge with one O(7)Mg6 octahedra,  an edgeedge with one O(5)Na2Mg4 octahedra, edges with two equivalent O(1)CeMg5 octahedra, edges with two equivalent O(9)Mg6 octahedra, edges with two equivalent O(8)NaCeMg4 octahedra, and edges with two equivalent O(2)NaMg5 octahedra. The corner-sharing octahedral tilt angles range from 0-11°. In the fifth O site, O(4) is bonded to two equivalent Mg(3); two Mg(5,5); and two equivalent Ce(1) atoms to form OCe2Mg4 octahedra that share corners with two equivalent O(4)Ce2Mg4 octahedra, corners with two equivalent O(6)Mg6 octahedra, corners with two equivalent O(5)Na2Mg4 octahedra, edges with four equivalent O(1)CeMg5 octahedra, edges with four equivalent O(3)Mg6 octahedra, and edges with four equivalent O(8)NaCeMg4 octahedra. The corner-sharing octahedra are not tilted. In the sixth O site, O(5) is bonded to two equivalent Na(1), two equivalent Mg(3), and two equivalent Mg(6) atoms to form ONa2Mg4 octahedra that share corners with two equivalent O(4)Ce2Mg4 octahedra; corners with two equivalent O(7)Mg6 octahedra; corners with two equivalent O(5)Na2Mg4 octahedra; edges with four equivalent O(3)Mg6 octahedra; edges with four equivalent O(8)NaCeMg4 octahedra; and edges with four O(2,2)NaMg5 octahedra. The corner-sharing octahedra are not tilted. In the seventh O site, O(6) is bonded to two equivalent Mg(1); two equivalent Mg(4); and two Mg(5,5) atoms to form OMg6 octahedra that share corners with two equivalent O(4)Ce2Mg4 octahedra, corners with two equivalent O(6)Mg6 octahedra, corners with two equivalent O(7)Mg6 octahedra, edges with four equivalent O(1)CeMg5 octahedra, edges with four equivalent O(3)Mg6 octahedra, and edges with four equivalent O(9)Mg6 octahedra. The corner-sharing octahedra are not tilted. In the eighth O site, O(7) is bonded to two equivalent Mg(2), two equivalent Mg(4), and two equivalent Mg(6) atoms to form OMg6 octahedra that share corners with two equivalent O(6)Mg6 octahedra; corners with two equivalent O(7)Mg6 octahedra; corners with two equivalent O(5)Na2Mg4 octahedra; edges with four equivalent O(3)Mg6 octahedra; edges with four equivalent O(9)Mg6 octahedra; and edges with four O(2,2)NaMg5 octahedra. The corner-sharing octahedra are not tilted. In the ninth O site, O(8) is bonded to one Na(1), two equivalent Mg(3), two equivalent Mg(7), and one Ce(1) atom to form ONaCeMg4 octahedra that share corners with two equivalent O(9)Mg6 octahedra; corners with four equivalent O(8)NaCeMg4 octahedra; edges with two equivalent O(4)Ce2Mg4 octahedra; edges with two equivalent O(1)CeMg5 octahedra; edges with two equivalent O(5)Na2Mg4 octahedra; edges with two O(2,2)NaMg5 octahedra; and edges with four equivalent O(3)Mg6 octahedra. The corner-sharing octahedral tilt angles range from 0-8°. In the tenth O site, O(9) is bonded to one Mg(1), one Mg(2), two equivalent Mg(4), and two equivalent Mg(7) atoms to form OMg6 octahedra that share corners with two equivalent O(8)NaCeMg4 octahedra; corners with four equivalent O(9)Mg6 octahedra; edges with two equivalent O(1)CeMg5 octahedra; edges with two equivalent O(6)Mg6 octahedra; edges with two equivalent O(7)Mg6 octahedra; edges with two O(2,2)NaMg5 octahedra; and edges with four equivalent O(3)Mg6 octahedra. The corner-sharing octahedral tilt angles range from 0-5°.