SrMg6HfO8 is alpha Po-derived structured and crystallizes in the tetragonal P4/mmm space group. Sr(1) is bonded to two equivalent O(1) and four equivalent O(3) atoms to form SrO6 octahedra that share corners with two equivalent Hf(1)O6 octahedra, corners with four equivalent Sr(1)O6 octahedra, edges with four equivalent Mg(1)O6 octahedra, and edges with eight equivalent Mg(3)O6 octahedra. The corner-sharing octahedra are not tilted. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form MgO6 octahedra that share corners with two equivalent Mg(2)O6 octahedra, corners with four equivalent Mg(1)O6 octahedra, edges with four equivalent Sr(1)O6 octahedra, and edges with eight equivalent Mg(3)O6 octahedra. The corner-sharing octahedra are not tilted. In the second Mg site, Mg(2) is bonded to two equivalent O(2) and four equivalent O(4) atoms to form MgO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with four equivalent Mg(2)O6 octahedra, edges with four equivalent Hf(1)O6 octahedra, and edges with eight equivalent Mg(3)O6 octahedra. The corner-sharing octahedra are not tilted. In the third Mg site, Mg(3) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form MgO6 octahedra that share corners with six equivalent Mg(3)O6 octahedra, edges with two equivalent Sr(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, edges with two equivalent Hf(1)O6 octahedra, and edges with four equivalent Mg(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-8°. Hf(1) is bonded to two equivalent O(1) and four equivalent O(4) atoms to form HfO6 octahedra that share corners with two equivalent Sr(1)O6 octahedra, corners with four equivalent Hf(1)O6 octahedra, edges with four equivalent Mg(2)O6 octahedra, and edges with eight equivalent Mg(3)O6 octahedra. The corner-sharing octahedra are not tilted. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Sr(1), four equivalent Mg(3), and one Hf(1) atom to form OSrHfMg4 octahedra that share corners with six equivalent O(1)SrHfMg4 octahedra, edges with four equivalent O(4)Hf2Mg4 octahedra, edges with four equivalent O(2)Mg6 octahedra, and edges with four equivalent O(3)Sr2Mg4 octahedra. The corner-sharing octahedral tilt angles range from 0-8°. In the second O site, O(2) is bonded to one Mg(1), one Mg(2), and four equivalent Mg(3) atoms to form OMg6 octahedra that share corners with six equivalent O(2)Mg6 octahedra, edges with four equivalent O(4)Hf2Mg4 octahedra, edges with four equivalent O(3)Sr2Mg4 octahedra, and edges with four equivalent O(1)SrHfMg4 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. In the third O site, O(3) is bonded to two equivalent Sr(1), two equivalent Mg(1), and two equivalent Mg(3) atoms to form OSr2Mg4 octahedra that share corners with two equivalent O(4)Hf2Mg4 octahedra, corners with four equivalent O(3)Sr2Mg4 octahedra, edges with four equivalent O(2)Mg6 octahedra, edges with four equivalent O(3)Sr2Mg4 octahedra, and edges with four equivalent O(1)SrHfMg4 octahedra. The corner-sharing octahedra are not tilted. In the fourth O site, O(4) is bonded to two equivalent Mg(2), two equivalent Mg(3), and two equivalent Hf(1) atoms to form OHf2Mg4 octahedra that share corners with two equivalent O(3)Sr2Mg4 octahedra, corners with four equivalent O(4)Hf2Mg4 octahedra, edges with four equivalent O(4)Hf2Mg4 octahedra, edges with four equivalent O(2)Mg6 octahedra, and edges with four equivalent O(1)SrHfMg4 octahedra. The corner-sharing octahedra are not tilted.
SrMg6HfO8 is alpha Po-derived structured and crystallizes in the tetragonal P4/mmm space group. Sr(1) is bonded to two equivalent O(1) and four equivalent O(3) atoms to form SrO6 octahedra that share corners with two equivalent Hf(1)O6 octahedra, corners with four equivalent Sr(1)O6 octahedra, edges with four equivalent Mg(1)O6 octahedra, and edges with eight equivalent Mg(3)O6 octahedra. The corner-sharing octahedra are not tilted. Both Sr(1)-O(1) bond lengths are 2.42 Å. All Sr(1)-O(3) bond lengths are 2.28 Å. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form MgO6 octahedra that share corners with two equivalent Mg(2)O6 octahedra, corners with four equivalent Mg(1)O6 octahedra, edges with four equivalent Sr(1)O6 octahedra, and edges with eight equivalent Mg(3)O6 octahedra. The corner-sharing octahedra are not tilted. Both Mg(1)-O(2) bond lengths are 2.24 Å. All Mg(1)-O(3) bond lengths are 2.28 Å. In the second Mg site, Mg(2) is bonded to two equivalent O(2) and four equivalent O(4) atoms to form MgO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with four equivalent Mg(2)O6 octahedra, edges with four equivalent Hf(1)O6 octahedra, and edges with eight equivalent Mg(3)O6 octahedra. The corner-sharing octahedra are not tilted. Both Mg(2)-O(2) bond lengths are 2.26 Å. All Mg(2)-O(4) bond lengths are 2.28 Å. In the third Mg site, Mg(3) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form MgO6 octahedra that share corners with six equivalent Mg(3)O6 octahedra, edges with two equivalent Sr(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, edges with two equivalent Hf(1)O6 octahedra, and edges with four equivalent Mg(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-8°. The Mg(3)-O(3) bond length is 2.25 Å. The Mg(3)-O(4) bond length is 2.25 Å. Both Mg(3)-O(1) bond lengths are 2.29 Å. Both Mg(3)-O(2) bond lengths are 2.28 Å. Hf(1) is bonded to two equivalent O(1) and four equivalent O(4) atoms to form HfO6 octahedra that share corners with two equivalent Sr(1)O6 octahedra, corners with four equivalent Hf(1)O6 octahedra, edges with four equivalent Mg(2)O6 octahedra, and edges with eight equivalent Mg(3)O6 octahedra. The corner-sharing octahedra are not tilted. Both Hf(1)-O(1) bond lengths are 2.08 Å. All Hf(1)-O(4) bond lengths are 2.28 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Sr(1), four equivalent Mg(3), and one Hf(1) atom to form OSrHfMg4 octahedra that share corners with six equivalent O(1)SrHfMg4 octahedra, edges with four equivalent O(4)Hf2Mg4 octahedra, edges with four equivalent O(2)Mg6 octahedra, and edges with four equivalent O(3)Sr2Mg4 octahedra. The corner-sharing octahedral tilt angles range from 0-8°. In the second O site, O(2) is bonded to one Mg(1), one Mg(2), and four equivalent Mg(3) atoms to form OMg6 octahedra that share corners with six equivalent O(2)Mg6 octahedra, edges with four equivalent O(4)Hf2Mg4 octahedra, edges with four equivalent O(3)Sr2Mg4 octahedra, and edges with four equivalent O(1)SrHfMg4 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. In the third O site, O(3) is bonded to two equivalent Sr(1), two equivalent Mg(1), and two equivalent Mg(3) atoms to form OSr2Mg4 octahedra that share corners with two equivalent O(4)Hf2Mg4 octahedra, corners with four equivalent O(3)Sr2Mg4 octahedra, edges with four equivalent O(2)Mg6 octahedra, edges with four equivalent O(3)Sr2Mg4 octahedra, and edges with four equivalent O(1)SrHfMg4 octahedra. The corner-sharing octahedra are not tilted. In the fourth O site, O(4) is bonded to two equivalent Mg(2), two equivalent Mg(3), and two equivalent Hf(1) atoms to form OHf2Mg4 octahedra that share corners with two equivalent O(3)Sr2Mg4 octahedra, corners with four equivalent O(4)Hf2Mg4 octahedra, edges with four equivalent O(4)Hf2Mg4 octahedra, edges with four equivalent O(2)Mg6 octahedra, and edges with four equivalent O(1)SrHfMg4 octahedra. The corner-sharing octahedra are not tilted.