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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Cooling-Rate-Driven Polymorphism and Vacancy Ordering in Ce 2 MnGe 6 Intergrowth Phases

Intergrowth phases in intermetallic systems provide a compelling framework for investigating structure–property relationships as a function of crystallographic subunit stacking. In this study, we examine the influence of Mn vacancy ordering on subunit stacking and reassign the structure of Ce 2 MnGe 6 to a monoclinic C2/m space group (a = 8.3486(17) Å, b = 8.6181(18) Å, c = 10.778(2) Å, β = 101.17(2)°). Additionally, we report a monoclinic polymorph of the Ln 2 MGe 6 family characterized as a tripled c-axis supercell derivative of monoclinic Ce 2 MnGe 6 , 3×c-Ce 2 MnGe 6 (a = 8.3482(16) Å, b = 8.6179(18) Å, c = 31.813(6) Å, β = 93.763(7)°). This polymorph emerges under rapid cooling conditions during the synthesis and offers insight into the structural relationship between the orthorhombic and monoclinic variants of the Ln 2 MGe 6 phases. Notably, the supercell form of Ce 2 MnGe 6 (3×c-Ce 2 MnGe 6 ) exhibits increased electrical resistivity and suggests enhanced Zintl-like behavior, potentially indicating greater thermodynamic stability relative to the parent monoclinic phase.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Atomic-scale visualization of topological spin textures in the chiral magnet MnGe

Peeking into magnetic textures Topological spin textures hold promise as robust carriers of information and have been observed in bulk materials with a specific crystal structure. One of these materials, manganese germanide (MnGe), exhibits unusual textures in bulk form. Repicky et al . used spin-polarized scanning tunneling microscopy to study surface magnetism in thin films of MnGe. Achieving high spatial resolution, the researchers observed stripe-like features consistent with a helical state. In regions where the film was slightly curved due to strain, the intersection of domain walls led to characteristic closed patterns that could be manipulated with current/voltage pulses. —JS

Science & Technology - Other Topics↗
DOE OSTI2020

Materials Data on Lu(MnGe)2 by Materials Project

Lu(MnGe)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Lu is bonded in a 8-coordinate geometry to eight equivalent Ge atoms. All Lu–Ge bond lengths are 3.03 Å. Mn is bonded to four equivalent Ge atoms to form a mixture of corner and edge-sharing MnGe4 tetrahedra. All Mn–Ge bond lengths are 2.42 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Lu, four equivalent Mn, and one Ge atom. The Ge–Ge bond length is 2.53 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sr(MnGe)2 by Materials Project

Sr(MnGe)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sr is bonded in a distorted body-centered cubic geometry to eight equivalent Ge atoms. All Sr–Ge bond lengths are 3.27 Å. Mn is bonded to four equivalent Ge atoms to form a mixture of edge and corner-sharing MnGe4 tetrahedra. All Mn–Ge bond lengths are 2.44 Å. Ge is bonded in a 4-coordinate geometry to four equivalent Sr and four equivalent Mn atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Np(MnGe)2 by Materials Project

Np(MnGe)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Np is bonded in a 8-coordinate geometry to eight equivalent Mn and eight equivalent Ge atoms. All Np–Mn bond lengths are 3.24 Å. All Np–Ge bond lengths are 3.10 Å. Mn is bonded to four equivalent Np and four equivalent Ge atoms to form a mixture of edge, face, and corner-sharing MnNp4Ge4 tetrahedra. All Mn–Ge bond lengths are 2.37 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Np, four equivalent Mn, and one Ge atom. The Ge–Ge bond length is 2.55 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Th(MnGe)2 by Materials Project

Th(MnGe)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Th is bonded in a 8-coordinate geometry to eight equivalent Ge atoms. All Th–Ge bond lengths are 3.15 Å. Mn is bonded to four equivalent Ge atoms to form a mixture of edge and corner-sharing MnGe4 tetrahedra. All Mn–Ge bond lengths are 2.45 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Th, four equivalent Mn, and one Ge atom. The Ge–Ge bond length is 2.67 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tm(MnGe)2 by Materials Project

Tm(MnGe)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Tm is bonded in a 8-coordinate geometry to eight equivalent Ge atoms. All Tm–Ge bond lengths are 3.04 Å. Mn is bonded to four equivalent Ge atoms to form a mixture of corner and edge-sharing MnGe4 tetrahedra. All Mn–Ge bond lengths are 2.42 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Tm, four equivalent Mn, and one Ge atom. The Ge–Ge bond length is 2.55 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tb3(MnGe)4 by Materials Project

Tb3(MnGe)4 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. there are two inequivalent Tb sites. In the first Tb site, Tb is bonded in a 12-coordinate geometry to six equivalent Mn and six Ge atoms. There are two shorter (3.05 Å) and four longer (3.10 Å) Tb–Mn bond lengths. There are two shorter (2.98 Å) and four longer (3.03 Å) Tb–Ge bond lengths. In the second Tb site, Tb is bonded to six Ge atoms to form TbGe6 octahedra that share corners with four equivalent MnTb3Ge4 tetrahedra, edges with two equivalent TbGe6 octahedra, and edges with eight equivalent MnTb3Ge4 tetrahedra. There are four shorter (2.97 Å) and two longer (3.04 Å) Tb–Ge bond lengths. Mn is bonded to three equivalent Tb and four Ge atoms to form distorted MnTb3Ge4 tetrahedra that share a cornercorner with one TbGe6 octahedra, corners with five equivalent MnTb3Ge4 tetrahedra, edges with two equivalent TbGe6 octahedra, edges with six equivalent MnTb3Ge4 tetrahedra, and faces with four equivalent MnTb3Ge4 tetrahedra. The corner-sharing octahedral tilt angles are 57°. There are a spread of Mn–Ge bond distances ranging from 2.54–2.61 Å. There are two inequivalent Ge sites. In the first Ge site, Ge is bonded in a 9-coordinate geometry to three Tb and six equivalent Mn atoms. In the second Ge site, Ge is bonded in a 9-coordinate geometry to six Tb, two equivalent Mn, and one Ge atom. The Ge–Ge bond length is 2.78 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SmY(MnGe)4 by Materials Project

SmY(MnGe)4 crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. Sm is bonded in a 8-coordinate geometry to eight equivalent Ge atoms. All Sm–Ge bond lengths are 3.10 Å. Y is bonded in a 8-coordinate geometry to eight equivalent Ge atoms. All Y–Ge bond lengths are 3.09 Å. Mn is bonded to four Ge atoms to form a mixture of edge and corner-sharing MnGe4 tetrahedra. All Mn–Ge bond lengths are 2.43 Å. There are two inequivalent Ge sites. In the first Ge site, Ge is bonded in a 9-coordinate geometry to four equivalent Sm, four equivalent Mn, and one Ge atom. The Ge–Ge bond length is 2.65 Å. In the second Ge site, Ge is bonded in a 9-coordinate geometry to four equivalent Y, four equivalent Mn, and one Ge atom. The Ge–Ge bond length is 2.61 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MnGe by Materials Project

MnGe crystallizes in the cubic P2_13 space group. The structure is three-dimensional. Mn is bonded in a 7-coordinate geometry to seven equivalent Ge atoms. There are a spread of Mn–Ge bond distances ranging from 2.43–2.66 Å. Ge is bonded in a 7-coordinate geometry to seven equivalent Mn atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(MnGe)6 by Materials Project

Mg(MnGe)6 crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. Mg is bonded to eight Ge atoms to form distorted edge-sharing MgGe8 hexagonal bipyramids. There are two shorter (2.68 Å) and six longer (2.98 Å) Mg–Ge bond lengths. Mn is bonded in a 12-coordinate geometry to six Ge atoms. There are a spread of Mn–Ge bond distances ranging from 2.50–2.67 Å. There are three inequivalent Ge sites. In the first Ge site, Ge is bonded in a 8-coordinate geometry to one Mg, six equivalent Mn, and one Ge atom. The Ge–Ge bond length is 2.68 Å. In the second Ge site, Ge is bonded in a 6-coordinate geometry to six equivalent Mn atoms. In the third Ge site, Ge is bonded in a 9-coordinate geometry to three equivalent Mg and six equivalent Mn atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NdSm(MnGe)4 by Materials Project

SmNd(MnGe)4 crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. Sm is bonded in a 8-coordinate geometry to eight equivalent Ge atoms. All Sm–Ge bond lengths are 3.13 Å. Nd is bonded in a 8-coordinate geometry to eight equivalent Ge atoms. All Nd–Ge bond lengths are 3.13 Å. Mn is bonded to four Ge atoms to form a mixture of corner and edge-sharing MnGe4 tetrahedra. All Mn–Ge bond lengths are 2.43 Å. There are two inequivalent Ge sites. In the first Ge site, Ge is bonded in a 9-coordinate geometry to four equivalent Nd, four equivalent Mn, and one Ge atom. The Ge–Ge bond length is 2.71 Å. In the second Ge site, Ge is bonded in a 9-coordinate geometry to four equivalent Sm, four equivalent Mn, and one Ge atom. The Ge–Ge bond length is 2.67 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca(MnGe)2 by Materials Project

CaMn2Ge2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ca is bonded in a 8-coordinate geometry to eight equivalent Ge atoms. All Ca–Ge bond lengths are 3.14 Å. Mn is bonded to four equivalent Ge atoms to form a mixture of edge and corner-sharing MnGe4 tetrahedra. All Mn–Ge bond lengths are 2.44 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Ca, four equivalent Mn, and one Ge atom. The Ge–Ge bond length is 2.73 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc(MnGe)6 by Materials Project

ScMn6Ge6 crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. Sc is bonded to eight Ge atoms to form distorted edge-sharing ScGe8 hexagonal bipyramids. There are two shorter (2.74 Å) and six longer (2.96 Å) Sc–Ge bond lengths. Mn is bonded in a 12-coordinate geometry to six Ge atoms. There are a spread of Mn–Ge bond distances ranging from 2.50–2.67 Å. There are three inequivalent Ge sites. In the first Ge site, Ge is bonded in a 8-coordinate geometry to one Sc, six equivalent Mn, and one Ge atom. The Ge–Ge bond length is 2.61 Å. In the second Ge site, Ge is bonded in a 12-coordinate geometry to three equivalent Sc and six equivalent Mn atoms. In the third Ge site, Ge is bonded in a 6-coordinate geometry to six equivalent Mn atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(MnGe)2 by Materials Project

UMn2Ge2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. U is bonded in a 8-coordinate geometry to eight equivalent Mn and eight equivalent Ge atoms. All U–Mn bond lengths are 3.29 Å. All U–Ge bond lengths are 3.09 Å. Mn is bonded to four equivalent U and four equivalent Ge atoms to form a mixture of face, edge, and corner-sharing MnU4Ge4 tetrahedra. All Mn–Ge bond lengths are 2.41 Å. Ge is bonded in a 9-coordinate geometry to four equivalent U, four equivalent Mn, and one Ge atom. The Ge–Ge bond length is 2.51 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr(MnGe)2 by Materials Project

PrMn2Ge2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Pr is bonded in a 8-coordinate geometry to eight equivalent Ge atoms. All Pr–Ge bond lengths are 3.17 Å. Mn is bonded to four equivalent Ge atoms to form a mixture of corner and edge-sharing MnGe4 tetrahedra. All Mn–Ge bond lengths are 2.45 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Pr, four equivalent Mn, and one Ge atom. The Ge–Ge bond length is 2.76 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm(MnGe)2 by Materials Project

SmMn2Ge2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sm is bonded in a 8-coordinate geometry to eight equivalent Ge atoms. All Sm–Ge bond lengths are 3.13 Å. Mn is bonded to four equivalent Ge atoms to form a mixture of corner and edge-sharing MnGe4 tetrahedra. All Mn–Ge bond lengths are 2.45 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Sm, four equivalent Mn, and one Ge atom. The Ge–Ge bond length is 2.68 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y(MnGe)2 by Materials Project

YMn2Ge2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Y is bonded in a 8-coordinate geometry to eight equivalent Ge atoms. All Y–Ge bond lengths are 3.08 Å. Mn is bonded to four equivalent Ge atoms to form a mixture of corner and edge-sharing MnGe4 tetrahedra. All Mn–Ge bond lengths are 2.44 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Y, four equivalent Mn, and one Ge atom. The Ge–Ge bond length is 2.61 Å.

36 MATERIALS SCIENCE↗