Materials Data on Pr2MgSe4 by Materials Project
MgPr2Se4 crystallizes in the triclinic P-1 space group. The structure is two-dimensional and consists of one MgPr2Se4 sheet oriented in the (0, 0, 1) direction. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to four Se2- atoms to form MgSe4 tetrahedra that share a cornercorner with one MgSe6 octahedra, corners with two equivalent PrSe6 octahedra, and corners with six PrSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 59–64°. There are a spread of Mg–Se bond distances ranging from 2.55–2.62 Å. In the second Mg2+ site, Mg2+ is bonded to six Se2- atoms to form MgSe6 octahedra that share a cornercorner with one MgSe4 tetrahedra, corners with five PrSe4 tetrahedra, edges with two equivalent MgSe6 octahedra, and edges with four equivalent PrSe6 octahedra. There are a spread of Mg–Se bond distances ranging from 2.82–2.91 Å. There are four inequivalent Pr3+ sites. In the first Pr3+ site, Pr3+ is bonded to four Se2- atoms to form PrSe4 tetrahedra that share a cornercorner with one PrSe6 octahedra, corners with two equivalent MgSe6 octahedra, corners with two equivalent MgSe4 tetrahedra, and corners with four PrSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 58–65°. There are a spread of Pr–Se bond distances ranging from 2.81–2.85 Å. In the second Pr3+ site, Pr3+ is bonded to six Se2- atoms to form PrSe6 octahedra that share corners with two equivalent MgSe4 tetrahedra, corners with four PrSe4 tetrahedra, edges with two equivalent PrSe6 octahedra, and edges with four equivalent MgSe6 octahedra. There are a spread of Pr–Se bond distances ranging from 3.01–3.07 Å. In the third Pr3+ site, Pr3+ is bonded to four Se2- atoms to form PrSe4 tetrahedra that share a cornercorner with one PrSe6 octahedra, corners with two equivalent MgSe6 octahedra, corners with two equivalent MgSe4 tetrahedra, and corners with four PrSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 58–68°. There are a spread of Pr–Se bond distances ranging from 2.81–2.84 Å. In the fourth Pr3+ site, Pr3+ is bonded to four Se2- atoms to form PrSe4 tetrahedra that share a cornercorner with one MgSe6 octahedra, corners with two equivalent PrSe6 octahedra, corners with two equivalent MgSe4 tetrahedra, and corners with four PrSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–66°. There are a spread of Pr–Se bond distances ranging from 2.81–2.84 Å. There are eight inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to two equivalent Mg2+ and two Pr3+ atoms to form a mixture of distorted corner and edge-sharing SePr2Mg2 tetrahedra. In the second Se2- site, Se2- is bonded to two Mg2+ and two equivalent Pr3+ atoms to form distorted SePr2Mg2 tetrahedra that share corners with nine SePr2Mg2 tetrahedra and edges with three SePr3Mg tetrahedra. In the third Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to one Mg2+ and two Pr3+ atoms. In the fourth Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to three Pr3+ atoms. In the fifth Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to one Mg2+ and two Pr3+ atoms. In the sixth Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to one Mg2+ and two Pr3+ atoms. In the seventh Se2- site, Se2- is bonded to one Mg2+ and three Pr3+ atoms to form distorted SePr3Mg tetrahedra that share corners with nine SePr2Mg2 tetrahedra and edges with three SePr3Mg tetrahedra. In the eighth Se2- site, Se2- is bonded to two equivalent Mg2+ and two Pr3+ atoms to form distorted SePr2Mg2 tetrahedra that share corners with nine SePr2Mg2 tetrahedra and edges with three SePr3Mg tetrahedra.