DOE OSTI2020
MgPr2S4 crystallizes in the orthorhombic Pca2_1 space group. The structure is three-dimensional. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six S2- atoms to form MgS6 octahedra that share a cornercorner with one PrS6 octahedra, corners with two equivalent MgS6 octahedra, corners with four PrS7 pentagonal bipyramids, an edgeedge with one MgS6 octahedra, edges with four PrS6 octahedra, and edges with three PrS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 11–53°. There are a spread of Mg–S bond distances ranging from 2.52–3.00 Å. In the second Mg2+ site, Mg2+ is bonded to six S2- atoms to form MgS6 octahedra that share a cornercorner with one PrS6 octahedra, corners with two equivalent MgS6 octahedra, corners with four PrS7 pentagonal bipyramids, an edgeedge with one MgS6 octahedra, edges with four PrS6 octahedra, and edges with three PrS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 11–54°. There are a spread of Mg–S bond distances ranging from 2.53–2.87 Å. There are four inequivalent Pr3+ sites. In the first Pr3+ site, Pr3+ is bonded to six S2- atoms to form PrS6 octahedra that share a cornercorner with one MgS6 octahedra, corners with two equivalent PrS6 octahedra, corners with four PrS7 pentagonal bipyramids, an edgeedge with one PrS6 octahedra, edges with four MgS6 octahedra, and edges with three PrS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 11–54°. There are a spread of Pr–S bond distances ranging from 2.79–2.88 Å. In the second Pr3+ site, Pr3+ is bonded to six S2- atoms to form PrS6 octahedra that share a cornercorner with one MgS6 octahedra, corners with two equivalent PrS6 octahedra, corners with four PrS7 pentagonal bipyramids, an edgeedge with one PrS6 octahedra, edges with four MgS6 octahedra, and edges with three PrS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 11–53°. There are a spread of Pr–S bond distances ranging from 2.78–2.89 Å. In the third Pr3+ site, Pr3+ is bonded to seven S2- atoms to form distorted PrS7 pentagonal bipyramids that share corners with four MgS6 octahedra, corners with four PrS6 octahedra, edges with three MgS6 octahedra, edges with three PrS6 octahedra, and faces with two equivalent PrS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 14–72°. There are a spread of Pr–S bond distances ranging from 2.84–3.11 Å. In the fourth Pr3+ site, Pr3+ is bonded to seven S2- atoms to form distorted PrS7 pentagonal bipyramids that share corners with four MgS6 octahedra, corners with four PrS6 octahedra, edges with three MgS6 octahedra, edges with three PrS6 octahedra, and faces with two equivalent PrS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 16–72°. There are a spread of Pr–S bond distances ranging from 2.83–3.14 Å. There are eight inequivalent S2- sites. In the first S2- site, S2- is bonded to two Mg2+ and three Pr3+ atoms to form distorted SPr3Mg2 trigonal bipyramids that share corners with two equivalent SPr3Mg2 square pyramids, corners with three equivalent SPr3Mg tetrahedra, corners with two equivalent SPr3Mg2 trigonal bipyramids, edges with five SPr3Mg2 square pyramids, and edges with three SPr3Mg2 trigonal bipyramids. In the second S2- site, S2- is bonded to two Mg2+ and three Pr3+ atoms to form distorted SPr3Mg2 trigonal bipyramids that share corners with six SPr3Mg2 square pyramids, corners with two equivalent SPr3Mg tetrahedra, corners with two equivalent SPr3Mg2 trigonal bipyramids, edges with three SPr3Mg2 square pyramids, an edgeedge with one SPr3Mg tetrahedra, and edges with three SPr3Mg2 trigonal bipyramids. In the third S2- site, S2- is bonded to one Mg2+ and three Pr3+ atoms to form a mixture of distorted corner and edge-sharing SPr3Mg tetrahedra. In the fourth S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to one Mg2+ and three Pr3+ atoms. In the fifth S2- site, S2- is bonded to two Mg2+ and three Pr3+ atoms to form distorted SPr3Mg2 square pyramids that share a cornercorner with one SPr3Mg tetrahedra, corners with eight SPr3Mg2 trigonal bipyramids, edges with four SPr3Mg2 square pyramids, an edgeedge with one SPr3Mg tetrahedra, and edges with two SPr3Mg2 trigonal bipyramids. In the sixth S2- site, S2- is bonded to two Mg2+ and three Pr3+ atoms to form distorted SPr3Mg2 square pyramids that share corners with two equivalent SPr4Mg square pyramids, a cornercorner with one SPr3Mg tetrahedra, corners with six SPr3Mg2 trigonal bipyramids, edges with three SPr3Mg2 square pyramids, an edgeedge with one SPr3Mg tetrahedra, and edges with three SPr3Mg2 trigonal bipyramids. In the seventh S2- site, S2- is bonded to one Mg2+ and four Pr3+ atoms to form distorted SPr4Mg square pyramids that share corners with two equivalent SPr3Mg2 square pyramids, corners with two equivalent SPr3Mg tetrahedra, corners with two equivalent SPr4Mg trigonal bipyramids, edges with three SPr3Mg2 square pyramids, an edgeedge with one SPr3Mg tetrahedra, and edges with five SPr3Mg2 trigonal bipyramids. In the eighth S2- site, S2- is bonded to one Mg2+ and four Pr3+ atoms to form distorted SPr4Mg trigonal bipyramids that share corners with eight SPr3Mg2 square pyramids, corners with three equivalent SPr3Mg tetrahedra, edges with two SPr3Mg2 square pyramids, and edges with four SPr3Mg2 trigonal bipyramids.