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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on MgZn2 by Materials Project

MgZn2 is Hexagonal Laves structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Mg is bonded in a 12-coordinate geometry to four equivalent Mg and twelve Zn atoms. There are one shorter (3.17 Å) and three longer (3.21 Å) Mg–Mg bond lengths. There are a spread of Mg–Zn bond distances ranging from 3.03–3.08 Å. There are two inequivalent Zn sites. In the first Zn site, Zn is bonded to six equivalent Mg and six equivalent Zn atoms to form a mixture of edge, face, and corner-sharing ZnMg6Zn6 cuboctahedra. All Zn–Zn bond lengths are 2.62 Å. In the second Zn site, Zn is bonded to six equivalent Mg and six Zn atoms to form a mixture of edge, face, and corner-sharing ZnMg6Zn6 cuboctahedra. There are two shorter (2.57 Å) and two longer (2.68 Å) Zn–Zn bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgZn2 by Materials Project

MgZn2 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Mg is bonded in a 9-coordinate geometry to nine Zn atoms. There are a spread of Mg–Zn bond distances ranging from 2.73–2.98 Å. There are two inequivalent Zn sites. In the first Zn site, Zn is bonded in a 7-coordinate geometry to five equivalent Mg and two equivalent Zn atoms. Both Zn–Zn bond lengths are 2.64 Å. In the second Zn site, Zn is bonded in a 10-coordinate geometry to four equivalent Mg and four Zn atoms. Both Zn–Zn bond lengths are 2.64 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgZn2(PO4)2 by Materials Project

MgZn2(PO4)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six equivalent PO4 tetrahedra, corners with two equivalent ZnO5 trigonal bipyramids, and edges with two equivalent ZnO5 trigonal bipyramids. There are two shorter (2.00 Å) and four longer (2.21 Å) Mg–O bond lengths. Zn2+ is bonded to five O2- atoms to form distorted ZnO5 trigonal bipyramids that share a cornercorner with one MgO6 octahedra, corners with three equivalent PO4 tetrahedra, an edgeedge with one MgO6 octahedra, an edgeedge with one PO4 tetrahedra, and an edgeedge with one ZnO5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 61°. There are a spread of Zn–O bond distances ranging from 1.98–2.37 Å. P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three equivalent MgO6 octahedra, corners with three equivalent ZnO5 trigonal bipyramids, and an edgeedge with one ZnO5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 29–54°. There are a spread of P–O bond distances ranging from 1.54–1.57 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to one Mg2+, one Zn2+, and one P5+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to one Mg2+, one Zn2+, and one P5+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Zn2+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Mg2+, one Zn2+, and one P5+ atom.

36 MATERIALS SCIENCE↗
NASA NTRS1984

Intermediate phases in some rare earth-ruthenium systems

The phase equilibria and crystal structures of intermediate phases were investigated in eight representative RE-Ru systems using powder X-ray diffraction and metallographic techniques. The Fe3C, Mn5C2 and Er5Ru3 structures occur in all but the Ce-Ru systems. Phases analogous to Er5Ru3 possess an unknown crystal structure similar to Er5Rh3(I). MgCu2 and MgZn2 type Laves phases are encountered in the light rare earth and heavy rare earth systems, respectively, and RERu2 phases, where RE = Nd and Sm, possess both the Laves phase structures. An intermediate phase, NdRu, with an unknown structure, occurs only in the Nd-Ru system. A bcc structure with 40 atoms per unit cell is encountered in the phases Er3Ru2 and Y3Ru2. The behavior of cerium in Ce-Ru alloys is unique in that four unidentified structures, not encountered in other RE-Ru systems, have been encountered. Also a phase designated as Ce3Ru is found with the Th7Fe3 type structure.

Sharifrazi, P.↗